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IntroductionNJEC0029MODELS WITH EURO-OBD SYSTEMNJEC0029S01The ECM has an on board diagnostic system which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
Diagnostic Trouble Code (DTC) Mode 3 of ISO 15031-5
Freeze Frame data Mode 2 of ISO 15031-5
System Readiness Test (SRT) code Mode 1 of ISO 15031-5
1st Trip Diagnostic Trouble Code (1st Trip DTC) Mode 7 of ISO 15031-5
1st Trip Freeze Frame data
Test values and Test limits Mode 6 of ISO 15031-5
Calibration ID Mode 9 of ISO 15031-5
The above information can be checked using procedures listed in the table below.
X: Applicable Ð: Not applicable
DTC 1st trip DTCFreeze Frame
data1st trip Freeze
Frame dataSRT code Test value
ECM*3 X X*1ÐÐÐÐ
CONSULT-IIXXXXXÐ
GST X X*2 X Ð X X
*1: When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.
*2: 1st trip DTCs for self-diagnoses concerning SRT items cannot be shown on the GST display.
*3: In diagnostic test mode II (Self-diagnostic results), DTC is displayed on MI. DTC uses a set of four digit numbers. (If so equipped)
The malfunction indicator (MI) on the instrument panel lights up when the same malfunction is detected in two
consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to EC-123.)
MODELS WITHOUT EURO-OBD SYSTEMNJEC0029S02The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
Diagnostic Trouble Code (DTC)
Freeze Frame data
1st Trip Diagnostic Trouble Code (1st Trip DTC)
1st Trip Freeze Frame data
The above information can be checked using procedures listed in the table below.
X: Applicable Ð: Not applicable
DTC 1st trip DTC Freeze Frame data1st trip Freeze Frame
data
CONSULT-II X X X X
ECM*1 X X*2 Ð Ð
*1: In diagnostic test mode II (Self-diagnostic results), (1st trip) DTC is displayed on the MI by a set of four digit numbers.
*2: When the DTC and the 1st trip DTC appear on the display simultaneously, it is difficult to clearly distinguish one from the other.
Two Trip Detection LogicNJEC0030MODELS WITH EURO-OBD SYSTEMNJEC0030S01When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in
the ECM memory. The MI will not light up at this stage <1st trip>.
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored
in the ECM memory, and the MI lights up. The MI lights up at the same time when the DTC is stored <2nd
trip>.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Introduction
EC-57
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The ªtripº in the ªTwo Trip Detection Logicº means a driving mode in which self-diagnosis is performed during
vehicle operation. Specific on board diagnostic items will cause the ECM to light up or blink the MI, and store
DTC and Freeze Frame data, even in the 1st trip, as shown below.
X: Applicable Ð: Not applicable
ItemsMI DTC 1st trip DTC
1st trip 2nd trip
1st trip
displaying2nd trip
displaying1st trip
displaying2nd trip
displaying
BlinkingLighting
upBlinkingLighting
up
Misfire (Possible three way
catalyst damage)
Ð DTC: P0300 - P0304 is
being detectedX ÐÐÐÐÐ X Ð
Misfire (Possible three way
catalyst damage)
Ð DTC: P0300 - P0304 is
being detectedÐÐXÐÐXÐÐ
Fail-safe items (Refer to
EC-123.)Ð X Ð Ð X*1 Ð X*1 Ð
Except above Ð ÐÐXÐX XÐ
*1: Except ªECMº.
MODELS WITHOUT EURO-OBD SYSTEMNJEC0030S02When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in
the ECM memory. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored
in the ECM memory. <2nd trip> The ªtripº in the ªTwo Trip Detection Logicº means a driving mode in which
self-diagnosis is performed during vehicle operation. When the ECM enters the fail-safe mode (Refer to
EC-123), the DTC is stored in the ECM memory even in the 1st trip.
Emission-related Diagnostic InformationNJEC0031MODELS WITH EURO-OBD SYSTEMNJEC0031S01DTC and 1st Trip DTCNJEC0031S0101The 1st trip DTC (whose number is the same as the DTC number) is displayed for the latest self-diagnostic
result obtained. If the ECM memory was cleared previously, and the 1st trip DTC did not reoccur, the 1st trip
DTC will not be displayed. If a malfunction is detected during the 1st trip, the 1st trip DTC is stored in the ECM
memory. The MI will not light up (two trip detection logic). If the same malfunction is not detected in the 2nd
trip (meeting the required driving pattern), the 1st trip DTC is cleared from the ECM memory. If the same mal-
function is detected in the 2nd trip, both the 1st trip DTC and DTC are stored in the ECM memory and the MI
lights up. In other words, the DTC is stored in the ECM memory and the MI lights up when the same malfunc-
tion occurs in two consecutive trips. If a 1st trip DTC is stored and a non-diagnostic operation is performed
between the 1st and 2nd trips, only the 1st trip DTC will continue to be stored. For malfunctions that blink or
light up the MI during the 1st trip, the DTC and 1st trip DTC are stored in the ECM memory.
Procedures for clearing the DTC and the 1st trip DTC from the ECM memory are described in ªHow to Erase
Emission-related Diagnostic Informationº. Refer to EC-68.
For malfunctions in which 1st trip DTCs are displayed, refer to EC-66. These items are required by legal
regulations to continuously monitor the system/component. In addition, the items monitored non-continuously
are also displayed on CONSULT-II.
1st trip DTC is specified in Mode 7 of ISO 15031-5. 1st trip DTC detection occurs without lighting up the MI
and therefore does not warn the driver of a problem. However, 1st trip DTC detection will not prevent the
vehicle from being tested, for example during Inspection/Maintenance (I/M) tests.
When a 1st trip DTC is detected, check, print out or write down and erase (1st trip) DTC and Freeze Frame
data as specified in ªWork Flowº procedure Step II, refer to page EC-96. Then perform ªDTC Confirmation
Procedureº or ªOverall Function Checkº to try to duplicate the problem. If the malfunction is duplicated, the
item requires repair.
How to read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
With CONSULT-II/With GST
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Two Trip Detection Logic (Cont'd)
EC-58
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CONSULT-II or GST (Generic Scan Tool) Examples: P0340, P1320, P0705, P0750, etc.
These DTCs are prescribed by ISO 15031-6.
(CONSULT-II also displays the malfunctioning component or system.)
+1st trip DTC No. is the same as DTC No.
+Output of a DTC indicates a malfunction. However, Mode II and GST do not indicate whether the
malfunction is still occurring or has occurred in the past and has returned to normal.
CONSULT-II can identify malfunction status as shown below. Therefore, using CONSULT-II (if avail-
able) is recommended.
A sample of CONSULT-II display for DTC is shown below. DTC or 1st trip DTC of a malfunction is displayed
in SELF-DIAGNOSTIC RESULTS mode of CONSULT-II. Time data indicates how many times the vehicle was
driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be ª0º.
If a 1st trip DTC is stored in the ECM, the time data will be ª[1t]º.
SEF698X
Freeze Frame Data and 1st Trip Freeze Frame DataNJEC0031S0102The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant
temperature, short term fuel trim, long term fuel trim, engine speed, vehicle speed, absolute throttle position,
base fuel schedule and intake air temperature at the moment a malfunction is detected.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data.
The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II or
GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
details, see EC-84.
Only one set of freeze frame data (either 1st trip freeze frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no prior-
ity for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MI on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
Priority Items
1Freeze frame data Misfire Ð DTC: P0300 - P0304 (0300 - 0304)
Fuel Injection System Function Ð DTC: P0171 (0171), P0172 (0172)
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data
For example, the EGR malfunction (Priority: 2) was detected and the freeze frame data was stored in the 2nd
trip. After that when the misfire (Priority: 1) is detected in another trip, the freeze frame data will be updated
from the EGR malfunction to the misfire. The 1st trip freeze frame data is updated each time a different mal-
function is detected. There is no priority for 1st trip freeze frame data. However, once freeze frame data is
stored in the ECM memory, 1st trip freeze data is no longer stored (because only one freeze frame data or
1st trip freeze frame data can be stored in the ECM). If freeze frame data is stored in the ECM memory and
freeze frame data with the same priority occurs later, the first (original) freeze frame data remains unchanged
in the ECM memory.
Both 1st trip freeze frame data and freeze frame data (along with the DTCs) are cleared when the ECM
memory is erased. Procedures for clearing the ECM memory are described in ªHow to Erase Emission-related
Diagnostic Informationº. Refer to EC-68.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-59
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System Readiness Test (SRT) CodeNJEC0031S0103System Readiness Test (SRT) code is specified in Mode 1 of ISO 15031-5.
As part of an emissions test for Inspection & Maintenance (I/M), certain states require the status of SRT be
used to indicate whether the ECM has completed self-diagnosis of major emission systems and components.
Completion must be verified in order for the emissions inspection to proceed.
If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating ªINCMPº,
use the information in this Service Manual to set the SRT to ªCMPLTº.
In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT
status will indicate ªCMPLTº for each application system. Once set as ªCMPLTº, the SRT status remains
ªCMPLTº until the self-diagnosis memory is erased.
Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's
normal driving pattern; the SRT will indicate ªINCMPº for these items.
NOTE:
The SRT will also indicate ªINCMPº if the self-diagnosis memory is erased for any reason or if the ECM
memory power supply is interrupted for several hours.
If, during the state emissions inspection, the SRT indicates ªCMPLTº for all test items, the inspector will con-
tinue with the emissions test. However, if the SRT indicates ªINCMPº for one or more of the SRT items the
vehicle is returned to the customer untested.
NOTE:
If MI is ªONº during the state emissions inspection, the vehicle is also returned to the customer untested even
though the SRT indicates ªCMPLTº for all test items. Therefore, it is important to check SRT (ªCMPLTº) and
DTC (No DTCs) before the inspection.
SRT ItemNJEC0031S0107The table below shows required self-diagnostic items to set the SRT to ªCMPLTº.
SRT item
(CONSULT-II indica-
tion)Perfor-
mance Pri-
ority*1Required self-diagnostic items to set the SRT to ªCMPLTºCorresponding
DTC No.
CATALYST 3 Three way catalyst function P0420
O2 SENSOR 3 Heated oxygen sensor 1 (front) (circuit) P0130
Heated oxygen sensor 1 (front) (lean shift monitoring) P0131
Heated oxygen sensor 1 (front) (rich shift monitoring) P0132
Heated oxygen sensor 1 (front) (response monitoring) P0133
Heated oxygen sensor 1 (front) (high voltage) P0134
Heated oxygen sensor 2 (rear) (min. voltage monitoring) P0137
Heated oxygen sensor 2 (rear) (max. voltage monitoring) P0138
Heated oxygen sensor 2 (rear) (response monitoring) P0139
Heated oxygen sensor 2 (rear) (high voltage) P0140
O2 SEN HEATER 3 Front heated oxygen sensor 1 heater (front) P0135
Rear heated oxygen sensor 1 heater (rear) P0141
EGR SYSTEM
(If so equipped)3 EGR function (close) P0400
1 EGR function (open) P1402
*1: If completion of several SRTs is required, perform driving patterns (DTC confirmation procedure), one by one based on the priority
for models with CONSULT-II.
SRT Set TimingNJEC0031S0108SRT is set as ªCMPLTº after self-diagnosis has been performed one or more times. Completion of SRT is done
regardless of whether the result is OK or NG. The set timing is different between OK and NG results and is
shown in the table below.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-60
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Self-diagnosis resultExample
DiagnosisIgnition cycle
¬ON®OFF¬ON®OFF¬ON®OFF¬ON®
All OK Case 1 P0400 OK (1) Ð (1) OK (2) Ð (2)
P0402 OK (1) Ð (1) Ð (1) OK (2)
P1402 OK (1) OK (2) Ð (2) Ð (2)
SRT of EGR ªCMPLTº ªCMPLTº ªCMPLTº ªCMPLTº
Case 2 P0400 OK (1) Ð (1) Ð (1) Ð (1)
P0402 Ð (0) Ð (0) OK (1) Ð (1)
P1402 OK (1) OK (2) Ð (2) Ð (2)
SRT of EGR ªINCMPº ªINCMPº ªCMPLTº ªCMPLTº
NG exists Case 3 P0400 OK OK Ð Ð
P0402 Ð Ð Ð Ð
P1402 NG Ð NGNG
(Consecutive NG)
(1st trip)
DTC1st trip DTC Ð 1st trip DTCDTC
(= MIL ªONº)
SRT of EGR ªINCMPº ªINCMPº ªINCMPº ªCMPLTº
OK: Self-diagnosis is carried out and the result is OK.
NG: Self-diagnosis is carried out and the result is NG.
Ð: Self-diagnosis is not carried out.
When all SRT related self-diagnoses showed OK results in a single cycle (Ignition OFF-ON-OFF), the SRT
will indicate ªCMPLTº.®Case 1 above
When all SRT related self-diagnoses showed OK results through several different cycles, the SRT will indi-
cate ªCMPLTº at the time the respective self-diagnoses have at least one OK result.®Case 2 above
If one or more SRT related self-diagnoses showed NG results in 2 consecutive cycles, the SRT will also indi-
cate ªCMPLTº.®Case 3 above
The table above shows that the minimum number of cycles for setting SRT as ªINCMPº is one (1) for each
self-diagnosis (Case1&2)ortwo(2)foroneofself-diagnoses (Case 3). However, in preparation for the state
emissions inspection, it is unnecessary of each self-diagnosis to be executed twice (Case 3) for the following
reasons:
+The SRT will indicate ªCMPLTº at the time the respective self-diagnoses have one (1) OK result.
+The emissions inspection requires ªCMPLTº of the SRT only with OK self-diagnosis results.
+When, during SRT driving pattern, 1st trip DTC (NG) is detected prior to ªCMPLTº of SRT, the self-diag-
nosis memory must be erased from ECM after repair.
+If the 1st trip DTC is erased, all the SRT will indicate ªINCMPº.
NOTE:
SRT can be set as ªCMPLTº together with the DTC(s). Therefore, DTC check must always be carried out prior
to the state emission inspection even though the SRT indicates ªCMPLTº.
SRT Service ProcedureNJEC0031S0109If a vehicle has failed the state emissions inspection due to one or more SRT items indicating ªINCMPº, review
the flowchart diagnostic sequence on the next page.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-61
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NEF395A
*1 EC-58 *2 EC-62 *3 EC-63
How to Display SRT CodeNJEC0031S01101.With CONSULT-II
Selecting ªSRT STATUSº in ªDTC CONFIRMATIONº mode with CONSULT-II.
For items whose SRT codes are set, a ªCMPLTº is displayed on the CONSULT-II screen; for items whose
SRT codes are not set, ªINCMPº is displayed as shown below.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-62
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SEF821Y
2.With GST
Selecting Mode 1 with GST (Generic Scan Tool)
How to Set SRT CodeNJEC0031S0111To set all SRT codes, self-diagnosis for the items indicated above must be performed one or more times. Each
diagnosis may require a long period of actual driving under various conditions.
With CONSULT-II
Perform corresponding DTC Confirmation Procedure one by one based on ªPerformance Priorityº in the table
on EC-122.
Without CONSULT-II
The most efficient driving pattern in which SRT codes can be properly set is explained on the next page. The
driving pattern should be performed one or more times to set all SRT codes.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-63
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Driving Pattern=NJEC0031S0112
NEF321A
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-64