ISO 15031-5:2011

INTERNATIONAL ISO
STANDARD 15031-5
Second edition
2011-04-15
Road vehicles — Communication
between vehicle and external equipment
for emissions-related diagnostics —
Part 5:
Emissions-related diagnostic services
Véhicules routiers — Communications entre un véhicule et un
équipement externe pour le diagnostic relatif aux émissions —
Partie 5: Services de diagnostic relatif aux émissions

Reference number
©
ISO 2011
©  ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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Published in Switzerland
ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.2
3 Terms, definitions and abbreviated terms.3
3.1 Terms and definitions .3
3.2 Abbreviated terms .5
4 Conventions.6
5 Document overview.6
6 Technical requirements .6
6.1 General requirements .6
6.2 Diagnostic service requirements.7
6.3 Diagnostic message format.34
6.4 Byte Order Convention .38
6.5 Allowance for expansion and enhanced diagnostic services .38
6.6 Definition of PIDs for services 0x01 and 0x02.39
6.7 Format of data to be displayed .39
7 Diagnostic service definition for ISO 9141-2, ISO 14230-4, and SAE J1850.39
7.1 Service 0x01 — Request current powertrain diagnostic data .39
7.2 Service 0x02 — Request powertrain freeze frame data.44
7.3 Service 0x03 — Request emission-related diagnostic trouble codes .48
7.4 Service 0x04 — Clear/Reset emission-related diagnostic information .53
7.5 Service 0x05 — Request oxygen sensor monitoring test results .55
7.6 Service 0x06 — Request On-board monitoring test results for Specific monitored systems .60
7.7 Service 0x07 — Request emission-related diagnostic trouble codes detected during
current or last completed driving cycle .65
7.8 Service 0x08 — Request control of on-board system, test or component .66
7.9 Service 0x09 — Request vehicle information.69
8 Diagnostic service definition for ISO 15765-4 .83
8.1 Service 0x01 — Request current powertrain diagnostic data .83
8.2 Service 0x02 — Request powertrain freeze frame data.89
8.3 Service 0x03 — Request emission-related diagnostic trouble codes .95
8.4 Service 0x04 — Clear/Reset emission-related diagnostic information .98
8.5 Service 0x05 — Request oxygen sensor monitoring test results .100
8.6 Service 0x06 — Request on-board monitoring test results for specific monitored systems .100
8.7 Service 0x07 — Request emission-related diagnostic trouble codes detected during
current or last completed driving cycle .110
8.8 Service 0x08 — Request control of on-board system, test or component .111
8.9 Service 0x09 — Request vehicle information.115
8.10 Service 0x0A — Request emission-related diagnostic trouble codes with permanent
status .127
Bibliography.129

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15031-5 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
This second edition cancels and replaces the first edition (ISO 15031-5:2006), which has been technically
revised.
This part of ISO 15031 is technically equivalent to SAE J1979:2010, with the addition of new capabilities
required by revised regulations from the California Air Resources Board and revised regulations from the
European Commission.
ISO 15031 consists of the following parts, under the general title Road vehicles — Communication between
vehicle and external equipment for emissions-related diagnostics:
⎯ Part 1: General information and use case definition
⎯ Part 2: Guidance on terms, definitions, abbreviations and acronyms
⎯ Part 3: Diagnostic connector and related electrical circuits, specification and use
⎯ Part 4: External test equipment
⎯ Part 5: Emissions-related diagnostic services
⎯ Part 6: Diagnostic trouble code definitions
⎯ Part 7: Data link security
iv © ISO 2011 – All rights reserved

Introduction
0.1 Overview
ISO 15031 consists of a number of parts which, taken together, provide a coherent self-consistent set of
specifications to facilitate emissions-related diagnostics. ISO 15031-1 provides an introduction to the series of
International Standards. Parts 2 through 7 are based on SAE recommended practices. This part of ISO 15031
is based on SAE J1979.
This document set includes the communication between the vehicle's On-Board Diagnostic (OBD) systems
and test equipment implemented across vehicles within the scope of the legislated emissions-related OBD.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in accordance
with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers. When
mapped on this model, the services specified by ISO 15031 are broken into the following layers in accordance
with Table 1:
⎯ diagnostic services (layer 7), specified in
⎯ this part of ISO 15031,
⎯ ISO 27145-3 (WWH-OBD),
⎯ presentation layer (layer 6), specified in
⎯ ISO 15031-2, SAE J1930-DA,
⎯ this part of ISO 15031, SAE J1979-DA,
⎯ ISO 15031-6, SAE J2012-DA,
⎯ ISO 27145-2, SAE J2012-DA,
⎯ session layer services (layer 5), specified in
⎯ ISO 14229-2 support ISO 15765-4 DoCAN and ISO 14230-4 DoK-Line protocols,
⎯ ISO 14229-2 is not applicable to the SAE J1850 and ISO 9141-2 protocols,
⎯ transport layer services (layer 4), specified in
⎯ ISO 15765-2,
⎯ SAE J1850 defined in this part of ISO 15031,
⎯ ISO 9141-2 defined in this part of ISO 15031,
⎯ ISO 14230-4, defined in this part of ISO 15031,
⎯ network layer services (layer 3), specified in:
⎯ ISO 15765-2,
⎯ SAE J1850 defined in this part of ISO 15031,
⎯ ISO 9141-2 defined in this part of ISO 15031,
⎯ ISO 14230-4 defined in this part of ISO 15031,
⎯ data link layer (layer 2), specified in:
⎯ ISO 15765-4, ISO 11898-1, and ISO 11898-2,
⎯ SAE J1850,
⎯ ISO 9141-2,
⎯ ISO 14230-2,
⎯ physical layer (layer 1), specified in:
⎯ ISO 15765-4, ISO 11898-1, and ISO 11898-2,
⎯ SAE J1850,
⎯ ISO 9141-2,
⎯ ISO 14230-1.
1)
Table 1 — Legislated emissions-related OBD/WWH -OBD diagnostic
specifications applicable to the OSI layers
Emissions-related OBD communication Emissions-related WWH-OBD
Applicability OSI 7 layers
requirements communication requirements
Application (layer 7) ISO 15031-5 ISO 27145-3
ISO 15031-2, ISO 15031-5, ISO 15031-6 ISO 27145-2
Presentation
(layer 6) SAE J1930-DA/SAE J1979-DA/
SAE J2012-DA
SAE J2012-DA
Seven layer
Session (layer 5) ISO 14229-2 Not Applicable ISO 14229-2
according to
ISO/IEC 7498-1
Transport (layer 4)
and
ISO 15765-2 ISO 15031-5
ISO/IEC 10731
Network (layer 3)
ISO
ISO
ISO 15765-4
Data link (layer 2)
14230-4
14230-2
ISO 11898-1
SAE J1850 ISO 9141-2
ISO 11898-2
ISO
Physical (layer 1)
14230-1
1) World-Wide Harmonized.
vi © ISO 2011 – All rights reserved

0.2 SAE document reference concept
ISO 15031 references several SAE documents which contain all terms, data and DTC (diagnostic trouble
code) definitions. This is illustrated in Figure 1.
Additional information on the content of the referenced documents is given below:
⎯ SAE J1930: the document is concerned with a procedure for naming objects and systems and with the
set of words from which names are built. It references SAE J1930-DA which contains all standardized
naming objects, terms and abbreviations.
⎯ SAE J1979: the document is concerned with the definition of emissions-related diagnostic services
(diagnostic test modes). It references SAE J1979-DA which contains all standardized data items such as
PIDs, Test IDs, Monitor IDs and INFOTYPE IDs.
⎯ SAE J2012: the document is concerned with the procedure for defining emissions-related DTCs. It
references SAE J2012-DA which contains all standardized data items such as DTCs and FTBs (failure
type bytes).
ISO 15031-2
ISO 15031-5 ISO 15031-6
Terms, definitions,
Emissions-related Diagnostic trouble
abbreviations and
diagnostic services code (DTC) definitions
acronyms
SAE J2012-DA
SAE J1930-DA SAE J1979-DA OBD
Emissions-related Emissions-related Emissions-related
acronym definition data definition diagnostic trouble
code definition
SAE J1930
SAE J1979 SAE J2012
Terms, definitions
Emissions-related Diagnostic trouble
abbreviations and
diagnostic services code (DTC) definitions
acronyms
Key
1 SAE Digital Annexes
Figure 1 — SAE Digital Annex document reference
OBD regulations require passenger cars, and light, medium and heavy duty trucks, to support a minimum set
of diagnostic information to external (off-board) “generic” test equipment.
0.3 SAE J1979-DA (OBD) Digital Annex
This part of ISO 15031 references SAE J1979-DA. SAE J1979-DA is concerned with the definition of:
⎯ Parameter Identifiers (PIDs),
⎯ Test IDentifiers (TIDs),
⎯ OBD Monitor Identifiers (OBDMIDs),
⎯ Unit and Scaling Identifiers (UASIDs), and
⎯ INFOTYPEs (INFOTYPEs).
0.4 SAE Digital Annex revision procedure
New emissions-related regulatory requirements drive new in-vehicle technology to lower emissions. New
technology related OBD monitor data and DTCs need to be standardized to support the external (off-board)
“generic” test equipment. All relevant information is proposed by the automotive industry represented by
members of the appropriate SAE task force.
The revision request form and instructions for updating the registers to this part of ISO 15031 can be obtained
on the Registration Authority's website at:
http://www.sae.org/servlets/works/committeeHome.do?comtID=TEVDS14
The column titled “Resources” shows a document with the title: J1979-DA_Revision_Request_Form.doc.
Double click on the name and you will be asked to download the document with the file name:
SAE_J1979-DA_Revision_Request_Form.doc
Fill out the revision request form with your request.
Please send an e-mail with the completed revision request form as an attachment to:
SAE Headquarters
755 West Big Beaver Road
Suite 1600
Troy, MI 48084-4093, USA
Fax: +1 (248) 273-2494
Email: saej1979@sae.org
viii © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 15031-5:2011(E)

Road vehicles — Communication between vehicle and external
equipment for emissions-related diagnostics —
Part 5:
Emissions-related diagnostic services
1 Scope
This part of ISO 15031 is intended to satisfy the data reporting requirements of On-Board Diagnostic (OBD)
regulations in the United States and Europe, and any other region that may adopt similar requirements in the
future. This part of ISO 15031 specifies:
a) message formats for request and response messages,
b) timing requirements between request messages from external test equipment and response messages
from vehicles, and between those messages and subsequent request messages,
c) behaviour of both the vehicle and external test equipment if data is not available,
d) a set of diagnostic services, with corresponding content of request and response messages, to satisfy
OBD regulations.
This part of ISO 15031 includes capabilities required to satisfy OBD requirements for multiple regions, model
years, engine types, and vehicle types. Those regulations are not yet final for some regions, and are expected
to change in the future. This part of ISO 15031 makes no attempt to interpret the regulations and does not
include applicability of the included diagnostic services and data parameters for various vehicle applications.
The user of this part of ISO 15031 is responsible for verifying the applicability of each clause of this part of
ISO 15031 for a specific vehicle, engine, model year and region.
This part of ISO 15031 specifies diagnostic services and functionally addressed request/response messages
required to be supported by motor vehicles and external test equipment for diagnostic purposes which pertain
to motor vehicle emission-related data. Any external test equipment meeting the requirements of ISO 15031-4
use these messages to retrieve emissions-related information from the vehicle.
Each clause in this part of ISO 15031 which specifies additional details to existing sections of ISO 9141-2,
ISO 14230-4, SAE J1850, and ISO 15765-4 supersede those specifications.
This part of ISO 15031 references SAE J1979-DA (Digital Annex), which includes all definitions of PIDs,
OBDMIDs, TIDs and INFOTYPEs.
This part of ISO 15031 provides the mechanism to satisfy the requirements included in the country-specific
regulations and not all capabilities included in this part of ISO 15031 are required by the country-specific
regulations. This part of ISO 15031 is not considered a final authority for interpretation of the regulations.
Therefore readers should determine the applicability of capabilities defined in this part of ISO 15031 for their
own specific needs.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 7498-1, Information technology — Open Systems Interconnection — Basic Reference Model: The
Basic Model
ISO/IEC 10731, Information technology — Open Systems Interconnection — Basic Reference Model —
Conventions for the definition of OSI services
ISO 9141-2:1994, Road vehicles — Diagnostic systems — Part 2: CARB requirements for interchange of
digital information
2)
ISO 14229-2 , Road vehicles — Unified diagnostic services (UDS) — Part 2: Session layer services
ISO 14230-2, Road vehicles — Diagnostic systems — Keyword Protocol 2000 — Part 2: Data link layer
ISO 14230-4:2000, Road vehicles — Diagnostic systems — Keyword Protocol 2000 — Part 4: Requirements
for emission-related systems
ISO 15765-2, Road vehicles — Diagnostics on Controller Area Networks (CAN) — Part 2: Network layer
services
ISO 15765-4, Road vehicles — Diagnostics on Controller Area Networks (CAN) — Part 4: Requirements for
emissions-related systems
ISO 15031-1, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 1: General information and use case definition
ISO 15031-2, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 2: Guidance on terms, definitions, abbreviations, and acronyms
ISO 15031-3, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 3: Diagnostic connector and related electrical circuits, specification and use
ISO 15031-4, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 4: External test equipment
ISO 15031-6, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 6: Diagnostic trouble code definitions
SAE J1930-DA, Digital Annex of Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations,
and Acronyms
SAE J1979-DA, Digital Annex of E/E Diagnostic Test Modes
SAE J2012-DA, Digital Annex of Diagnostic Trouble Code Definitions and Failure Type Byte Definitions

2) To be published.
2 © ISO 2011 – All rights reserved

3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14229-2, ISO 14230-2, ISO 15031-2
and ISO 15765-2 and the following apply.
3.1.1
absolute throttle position sensor
value intended to represent the throttle opening
NOTE For systems where the output is proportional to the input voltage, this value is the percent of maximum input
signal. For systems where the output is inversely proportional to the input voltage, this value is 100 % minus the percent of
maximum input signal. Throttle position at idle usually indicates greater than 0 %, and throttle position at wide open throttle
usually indicates less than 100 %.
3.1.2
bank
specific group of cylinders sharing a common control sensor
NOTE 1 Bank 1 always contains cylinder number 1 and bank 2 the opposite bank.
NOTE 2 If there is only one bank, the DTCs for bank #1 DTCs are used, and the word bank may be omitted. With a
single “bank” system utilizing multiple sensors, bank #1 DTCs are used identifying the sensors as #1, #2, and #3 in order
as they move further away from the cylinder.
3.1.3
base fuel schedule
fuel calibration schedule programmed into the Powertrain Control Module or PROM when manufactured or
when updated by an off-board source, prior to any learned on-board correction
3.1.4
calculated load value
〈spark ignition vehicles〉 typically an indication of the current airflow divided by peak airflow at wide open
throttle as a function of rpm, where airflow is corrected for altitude and ambient temperature
NOTE 1 Both spark ignition and compression ignition vehicles can use an alternate definition that substitutes engine
torque in place of airflow in the calculation.
NOTE 2 This definition provides a number (without unit) and provides the service technician with an indication of the
percent engine capacity that is being used.
3.1.5
client
function that is part of the tester and that makes use of the diagnostic services
NOTE A tester normally makes use of other functions such as database management, specific interpretation, and
man-machine interface.
3.1.6
continuous monitoring
sampling at a rate no fewer than two samples per second
NOTE If, for control purposes, a computer input is sampled less frequently, the signal of the component may instead
be evaluated each time sampling occurs.
3.1.7
convention
Cvt
column integrated in each message table which marks each parameter included
NOTE The following conventions are used: C = Conditional: the parameter marked “C” in a request/response
message is present only under a condition specified in the bottom row of the message table. M = Mandatory: the
parameter marked “M” in a request/response message table is always present. U = User (optional): the parameter marked
“U” in a request/response message table is supplied depending on dynamic usage by the manufacturer. The convention
recommends a mnemonic, which might be used for implementation. In no case is the specified mnemonic ever a
mandatory requirement for any implementation.
3.1.8
electronic control unit
ECU
generic term for any electronic control unit
3.1.9
emissions-related DTC
DTC which is set when a malfunction causes vehicle emissions to exceed legislated emission thresholds or is
otherwise required to be set as specified by on-board diagnostics legislation (e.g. disables another part of the
diagnostic system)
NOTE Normally, the malfunction indicator (MI) is illuminated at the same time as the emissions-related DTC is set.
The determination of which DTCs are emissions-related is made by the vehicle manufacturer for each vehicle, as specified
by on-board diagnostic legislation.
3.1.10
fuel trim
FT
feedback adjustments to the base fuel schedule
NOTE Short-term fuel trim refers to dynamic or instantaneous adjustments. Long-term fuel trim refers to much more
gradual adjustments to the fuel calibration schedule than short-term trim adjustments. These long-term adjustments
compensate for vehicle differences and gradual changes that occur over time.
3.1.11
negative numbers
signed binary, the most significant bit (MSB) of the binary number used to indicate positive (0) / negative (1)
NOTE 1 2s complement: negative numbers are represented by complementing the binary number and then adding 1.
EXAMPLE – 0,99 = 8001 hex = 1000 0000 0000 0001 binary
0 = 0x0000 = 0000 0000 0000 0000 binary
+ 0,99 = 0x7FFF = 0111 1111 1111 1111 binary
NOTE 2 (– 0,99) + (+ 0,99) = 0.
3.1.12
number
expressed by this symbol “#”
3.1.13
P2, P3 timing parameter
application timing parameters for the ECU(s) and the external test equipment
4 © ISO 2011 – All rights reserved

3.1.14
P2 timing parameter
CAN_min
CAN application timing parameter with the minimum value for the ECU(s) and the external test equipment to
start the response message
3.1.15
P2 timing parameter
CAN_max
CAN application timing parameter with the maximum value for the ECU(s) and the external test equipment to
indicate a response message
3.1.16
P2 timing parameter
reload
CAN application timing parameter with the maximum value (P2 ) for external test equipment only
CAN_max
3.1.17
server
function that is part of an ECU that provides the diagnostic services
NOTE This part of ISO 15031 differentiates between the server, i.e. the function, and the electronic control unit so
that it remains independent from the implementation.
3.1.18
service
information exchange initiated by a client (external test equipment) in order to require diagnostic information
from a server (ECU) and/or to modify its behavior for diagnostic purposes
NOTE This is also the equivalent of test mode or mode.
3.2 Abbreviated terms
.con confirmation
.ind indication
.req request
CRC cyclic redundancy check
CVN calibration verification number
DTC diagnostic trouble code
ECM engine control module
ERR error detection byte
EWMA exponential weighted moving average
FF first frame
ISR interrupt service routine
LSB least significant bit
MI malfunction indicator
MIL malfunction indicator light
MSB most significant bit
N_PDU network protocol data unit
N/A not applicable
NRC negative response code
NVRAM non-volatile memory
OBDMID OBD monitor identifier
PID parameter identifier
PCI protocol control information
RSP in-frame response
SF single frame
SOM start of message
T_AE virtual transport interface address extension
T_Data [ ] virtual transport interface data field
T_Mtype virtual transport interface message type
T_Length virtual transport interface length information
T_PDU virtual transport interface protocol data unit
T_Result virtual transport interface result
T_SA virtual transport interface source address
T_TA virtual transport interface target address
T_TAtype virtual transport interface target address type
TCM transmission control module
TID test identifier
UASID unit and scaling identifier
VIN vehicle identification number
4 Conventions
ISO 15031 is based on the conventions specified in the OSI Service Conventions (ISO/IEC 10731) as they
apply for diagnostic services.
5 Document overview
Figure 2 illustrates the emissions-related OBD in ISO 15765-4, SAE J1850, ISO 9141-2, and ISO 14230-4.
The protocol initialization identifies whether ISO 15765-4 DoCAN or SAE J1850 or ISO 14230-4 DoK-Line or
ISO 9141-2 is the data link layer supported by the vehicle. ISO 15031 references the standards as an
applicable data link for emissions-related OBD.
This part of ISO 15031 specifies the applicable emissions-related diagnostic services. It specifies the data
record structures and references SAE J1930-DA, SAE J1979-DA and SAE J2012-DA which include all
emissions-related OBD data definitions.
6 Technical requirements
6.1 General requirements
The requirements specified in this clause are necessary to ensure proper operation of both the external test
equipment and the vehicle during diagnostic procedures. External test equipment, when using the messages
specified, shall not affect normal operation of the emission control system.
IMPORTANT — New emissions-related vehicle technology required the definition of new PIDs and
INFOTYPEs. The data parameter set for several new definitions exceed the specified limit of message
length for ISO 9141-2, ISO 14230-4 and SAE J1850 protocols. It is the vehicle manufacturer's
6 © ISO 2011 – All rights reserved

responsibility to implement the ISO 15765-4 DoCAN protocol in order to achieve legislative
compliance of the emissions-related OBD systems in the vehicle.
6.2 Diagnostic service requirements
6.2.1 Multiple responses to a single data request
The request messages are functional messages, which means that the external test equipment will request
data without knowledge of which ECU(s) on the vehicle will respond. In some vehicles, multiple ECUs may
respond with the information requested. Any external test equipment requesting information shall therefore
have provisions for receiving multiple responses.
IMPORTANT — All emissions-related OBD ECUs, which at least support one of the services defined in
this part of ISO 15031, shall support service 0x01 and PID 0x00. Service 0x01 with PID 0x00 is defined
as the universal “initialization/keep alive/ping” message for all emissions-related OBD ECUs.
Emissions-related diagnostic services
ISO 15031-1
Emissions OBD
General information
and use case definition
ISO 15031-5 SAE J1930-DA
Terms, .
Emissions-related
diagnostic services
OSI Layer 7
SAE J1979-DA
Application
PIDs, MIDs, RIDs,
INFOTYPES
ISO 15031-2,
ISO 15031-5,
ISO 15031-6
SAE J2012-DA
1 : 1
OSI Layer 6
Emissions-related
DTCs
Presentation
terms, data, DTCs
ISO 14229-2 ISO 14229-2
Not applicable
UDS
OSI Layer 5 UDS
(no document available)
Session Session layer services Session layer services
Standardized service Standardized service
Not applicable
primitive interface primitive interface
ISO 15765-4 SAE ISO ISO 14230-4
J1850 9141-2
ISO 15765-2
DoCAN ISO 15031-5
OSI Layer 4
Communication between vehicle and
Transport
Transport
external test equipment for
protocol
and
emissions-related diagnostics
network
layer services
Emissions-related diagnostic services
OSI Layer 3
ISO 15765-4 ISO 14230-4
Network
DoCAN
DoK-Line
ISO 11898-1
Requirements
CAN
for emissions-
Data link layer Requirements
related
for emissions-
and physical
ISO 14230-2
systems
related systems
DoK-Line
signalling
ISO 9141-2
OSI Layer 2
SAE J1850
Data link
Data Link
layer
Class B
CARB
Data
requirements
communi-
ISO 11898-2
for
cations
CAN
interchange
ISO 14230-1
network
High-speed
of digital
DoK-Line
interface
OSI Layer 1
medium
information
Physical
Physical
access unit
layer
Figure 2 — Emissions-related OBD in ISO 15765-4, SAE J1850, ISO 9141-2, and
ISO 14230-4 according to OSI model
8 © ISO 2011 – All rights reserved

6.2.2 Application timing parameter definition
6.2.2.1 Overview
The definition of P2 and P3 is included in this clause. A subscript is added to each timing parameter to identify
the protocol:
⎯ P2 , P3 : P2, P3 for ISO 9141-2 and ISO 14230-4 protocols
K-line K-line
⎯ P2 : P2 for SAE J1850 protocol
J1850
⎯ P2 : P2 for ISO 15765-4 protocol
CAN
IMPORTANT — The vehicle manufacturer is responsible for specifying a shorter P2 timing window
than specified in this part of ISO 15031 for each emission-related server/ECU in the vehicle in order to
make sure that network topology delays of the vehicle architecture are considered.
6.2.2.2 Definition for ISO 9141-2
For ISO 9141-2 interfaces, data link layer response time requirements (P1, P4) are specified in ISO 9141-2.
Table 2 specifies the application timing parameter values for P2 and P3.
Table 2 — Definition of ISO 9141-2 application timing parameter values
Minimum Maximum
Parameter value value Description
ms ms
P2 25 50 Time between external test equipment request message and the transmission
K-line
Key Bytes: of the ECU(s) response message(s). Each OBD ECU shall start sending its
0x08 0x08 response message within P2 after the request message has been correctly
K-line
received. Subsequent response messages shall also be transmitted within
P2 of the previous response message for multiple message responses.
K-line
P2 0 50 Time between external test equipment request message and the transmission
K-line
Key Bytes: of the ECU response message(s). The OBD ECU shall start sending its
0x94 0x94 response message within P2 after the request message has been correctly
K-line
received. Subsequent response messages shall also be transmitted within
P2 of the previous response message for multiple message responses.
K-line
P3 55 5000 Time between the end of an ECU(s) successful transmission of response
K-line
message(s) and start of new external test equipment request message. The
external test equipment may send a new request message if all response
messages related to the previously sent request message have been received
and if P3 minimum time has expired.
K-line
ECU implementation guideline: TX (transmit) and RX (receive) lines are
connected. Each transmitted byte is read back by the receiver in the ECU. Upon
the reception of a received byte, e.g. last byte of a request message
(checksum) from the tester, the ECU shall reset the P3 timer value to zero. If
the ECU supports the request message, it will start transmitting the response
message within the P2 timing window. Each transmitted byte will cause the P3
timer value to be reset. If the ECU does not support the request and does not
send a response message, then in a single OBD ECU system the P3 is started
after the last byte received of the request message. In a multiple OBD ECU
system a response message by one or more ECUs shall cause the P3 timer
value to be reset in all ECUs including any ECU not supporting the request
message.
6.2.2.3 Definition for ISO 14230-4
For ISO 14230-4 interfaces, data link layer response time requirements are specified in ISO 14230-4.
Table 3 specifies the application timing parameter values for P2 and P3.
Table 3 — Definitions of ISO 14230-4 application timing parameter values
Minimum Maximum
Parameter value value Description
ms ms
P2 25 50 Time between external test equipment request message and the transmission
K-line
of the ECU(s) response message(s). Each OBD ECU shall start sending its
response message within P2 after the request message has been correctly
K-line
received. Subsequent response messages shall also be transmitted within
P2 of the previous response message for multiple message responses.
K-line
P3 55 5000 Time between the end of an ECU(s) successful transmission of response
K-line
message(s) and start of new external test equipment request message. The
external test equipment may send a new request message if all response
messages related to the previously sent request message have been received
and if P3 minimum time has expired.
K-line
ECU implementation guideline: TX (transmit) and RX (receive) line are
connected. Each transmitted byte is read back by the receiver in the ECU.
Upon the reception of a received byte, e.g. last byte of a request message
(checksum) from the tester, the ECU shall reset the P3 timer value to zero. If
the ECU supports the request message, it will start transmitting the response
message within the P2 timing window. Each transmitted byte will cause the P3
timer value to be reset. If the ECU does not support the request and does not
send a response message, then in a single OBD ECU system, the P3 is started
with the last byte received of the request message. In a multiple OBD ECU
system, a response message by any one or more ECUs shall cause the P3
timer value to be reset in all ECUs including any ECU not supporting the
request message.
6.2.2.4 Data link layer interface adaptation
6.2.2.4.1 General information
This part of ISO 15031 makes use of the data link layer services defined in ISO 14230-2 for the transmission
and reception of diagnostic messages. This section defines the mapping of the virtual data link PDU (T_PDU)
in ISO 14229-2 onto the K-Line data link layer PDU (DL_PDU) in ISO 14230-2.
NOTE The data link layer services are used to perform the application layer and diagnostic session management
timing.
6.2.2.4.2 Mapping of data link independent service primitives onto K-Line data link dependent
service primitives
Table 4 specifies the mapping interface between the ISO 14230-2 DoK-Line Part 2: Data link layer services
and the ISO 14229-2 UDS Part 2.
Table 4 — Mapping of T_PDU service primitives onto DL_PDU service primitives
transport/network layer service primitives DoK-Line data link layer service primitives
(data link independent according to ISO 14229-2) (data link dependent according to ISO 14230-2)
T_Data.indication DL_Data.indication
T_DataSOM.indication DL_DataFB.indication
T_Data.confirm DL_Data.confirm
T_Data.request DL_Data.request
10 © ISO 2011 – All rights reserved

6.2.2.4.3 Mapping of T_PDU onto DL_PDU for message transmission
The parameters of the application layer protocol data unit defined to request the transmission of a diagnostic
service request/response are mapped in accordance with Table 5 onto the parameters of the data link layer
protocol data unit for the transmission of a message in the client/server.
Table 5 — Mapping of T_PDU parameter onto DL_PDU parameter
T_PDU parameter DL_PDU parameter
(data link independent according to ISO 14229-2) (DoK-Line data link dependent according to ISO 14230-2)
T_Mtype N/A (always set to "diagnostics")
T_SA DL_SA
T_TA DL_TA
T_TAtype DL_TAtype
T_AE N/A
T_Data [ ]
T_Length
T_Result
6.2.2.5 Implementation guidance example for ISO 9141-2 and ISO 14230-4 protocols
This subclause provides an implementation example for client/external test equipment and server/ECU. It is
assumed that the client (external test equipment) communicates to a vehicle with two (2) emission-related
OBD servers (ECUs). The client requests a CVN, which is only supported by server #1 (ECU#1) with two (2)
response messages. Server #2 (ECU#2) is not flash programmable. Figure 3 graphically depicts the timing
handling in the client and two (2) servers for a functionally addressed request message. A description
following Figure 3 references the points marked in the figure.
From a server point of view, there is no difference in the timing handling compared to a physically addressed
request message. The server shall reset the P3 timer value on each received byte regardless of whether
K-line
the byte is part of a request message or a response message from any other server or an echo from its
transmit line. There are several methods in which a server can implement the timing handling. The
implementation of timing parameters is not part of this part of ISO 15031 but has an important system supplier
responsibility. Some general server timing parameter implementation guidelines are described in this
subclause. The server time stamps each receiver interrupt event and restarts/resets the P3 timer or
K-line_server
timing value, e.g. ISR time stamps received byte, and processing of the received information is performed
outside the ISR. For simplification of the diagram, Figure 3 only shows a P3 restart after the reception
K-line_server
of the first byte and last byte (checksum) of a received message. The P3 restart is required on each
K-line_server
received byte. The received message can be either a request message from the client or a response message
from any other server connected and initialized by the 0x33 address. If the server has received a complete
message, it compares the target address with the 0x33 address.
Figure 3 shows the client and two (2) initialized servers connected via K-line (either ISO 9141-2 or
ISO 14230-4 protocol). The relevant events for the client and both servers are marked and described.
The diagnostic application of the client starts the transmission of a functionally addressed request message by issuing a
T_Data.request to its data link layer. The data link layer transmits the request message to the servers.
Both servers and the client receive a byte of a message via a receive interrupt by the UART. The ISR (interrupt service routine)
either restarts the P2 /P3 timers or time stamps the received byte.
K-line K-line
The completion of the request message is indicated in the client with T_Data.confirmation. When receiving the T_Data.confirmation,

the client starts its P2 and P3 timer, using the default reload values P2 and P3 .
K-line K-line K-line_max K-line_max
If the last message byte is received, each server checks whether the received message includes a target address which matches
the 0x33 address. If the result is a match (server #1 and #2), then the completion of the request message is indicated in the servers
via T_Data.indication and each server determines whether it supports the request and has a message available to respond with. If a
server determines that the address in the received message is different from 0x33, or if the address is a match but no response
needs to be sent (server #2), the P2 timer is stopped. Since the P3 timer has already been restarted, no further action is
K-line
required. If a response message is available and has to be sent (server #1, but not server #2), then the transmission of the

response message shall be started after P2 timing is expired.
K-line_min
Server #1 starts the response message by indicating a T_Data.request from the application to the data link layer and at the same

time stops its P2 timer.
K-line
12 © ISO 2011 – All rights reserved

Both servers and the client receive a byte of a message via a receive interrupt by the UART. The ISR (interrupt service routine)
restarts the P2 /P3 timers or time stamps the received byte and the client issues a T_Data_FB.indication to the application
K-line K-line
layer.
The completion of the response message is indicated in the client with T_Data.indication. When receiving the T_Data.indication, the

client starts its P2 and P3 timer, using the default reload values P2 and P3 .
K-line K-line K-line_max K-line_max
Both servers have received the last byte of a message via a receive interrupt by the UART. The ISR (interrupt service routine)
either resets the P2 /P3 timers or time stamps the received byte. The completion of the response message (e.g. length and
K-line K-line
checksum check) is indicated in server #1 via T_Data.confirmation. If server #1 does not want to s
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