Nissan Frontier D22. Manual - part 380

ON BOARD DIAGNOSTIC (OBD) SYSTEM

EC-623

[VG33E]

DTC AND 1ST TRIP DTC

The 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 MIL 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 malfunction is detected in the
2nd trip, both the 1st trip DTC and DTC are stored in the ECM memory and the MIL lights up. In other words,
the DTC is stored in the ECM memory and the MIL lights up when the same malfunction occurs in two consec-
utive 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 MIL 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

EC-632, "HOW

TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION"

For malfunctions in which 1st trip DTCs are displayed, refer to

EC-620

. These items are required by legal reg-

ulations 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 SAE J1979. 1st trip DTC detection occurs without lighting up the MIL and
therefore does not warn the driver of a malfunction. However, 1st trip DTC detection will not prevent the vehi-
cle 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 Work Flow procedure Step II, refer to

EC-641

. Then perform DTC Confirmation Procedure

or Overall Function Check to try to duplicate the malfunction. 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

CONSULT-II or GST (Generic Scan Tool) Examples: P0340, P0705, P0750, etc.
These DTCs are prescribed by SAE J2012.
(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, 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 available) is recommended.

A sample of CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion 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 [0].
If a 1st trip DTC is stored in the ECM, the time data will be [1t].

FREEZE FRAME DATA AND 1ST TRIP FREEZE FRAME DATA

The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant tem-
perature, short term fuel trim, long term fuel trim, engine speed, vehicle speed and absolute pressure 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

PBIB0911E

EC-624

[VG33E]

ON BOARD DIAGNOSTIC (OBD) SYSTEM

GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
details, see

EC-678

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 priority
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/MIL 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.

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 mem-
ory is erased. Procedures for clearing the ECM memory are described in

EC-632, "HOW TO ERASE EMIS-

SION-RELATED DIAGNOSTIC INFORMATION"

SYSTEM READINESS TEST (SRT) CODE

System Readiness Test (SRT) code is specified in Mode 1 of SAE J1979.
As part of enhanced emissions test for Inspection and Maintenance (I/M), certain states require that 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 “INCMP”, use
the information in this service manual to set the SRT to “CMPLT”.
In most cases, the ECM will automatically complete its self-diagnosis cycle during normal usage and the SRT
status will indicate “CMPLT” for each application system. Once set as “CMPLT”, the SRT status remains
“CMPLT” 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 and the SRT will indicate “INCMP” for these items.
NOTE:
The SRT will also indicate “INCMP” if the self-diagnosis memory is erased for any reason or if the ECM mem-
ory power supply is interrupted for several hours.
If, during the state emissions inspection, the SRT indicates “CMPLT” for all test items, the inspector will con-
tinue with the emissions test. However, if the SRT indicates “INCMP” for one or more of the SRT items, the
vehicle is returned to the customer untested.
NOTE:
If MIL is ON during the state emissions inspection, the vehicle is also returned to the customer untested even
though the SRT indicates “CMPLT” for all test items. Therefore, it is important to check SRT (“CMPLT”) and
DTC (No DTCs) before the inspection.

Priority

Items

Freeze frame data

Misfire — DTC: P0300 - P0306
Fuel Injection System Function — DTC: P0171, P0172, P0174, P0175

Except the above items (Includes A/T related items)

1st trip freeze frame data

ON BOARD DIAGNOSTIC (OBD) SYSTEM

EC-625

[VG33E]

SRT Item

The following table shows required self-diagnostic items to set the SRT to “CMPLT”.

*: 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 Timing

SRT is set as “CMPLT” 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.

OK: Self-diagnosis is carried out and the result is OK.
NG: Self-diagnosis is carried out and the result is OK.
–: Self-diagnosis is not carried out.

SRT item

(CONSULT-II indication)

Perfor-

mance Pri-

ority *

Required self-diagnostic items to set the SRT to “CMPLT”

Corresponding DTC No.

CATALYST

Three way catalyst function

P0420, P0430

EVAPRAITIVE SYSTEM

EVAP control system

P0442, P1442

EVAP control system

P0456, P1456

EVAP control system purge flow monitoring

P0441

HO2S

Heated oxygen sensor 1

P0133, P0153

Heated oxygen sensor 1

P1143, P1163

Heated oxygen sensor 1

P1144, P1164

Heated oxygen sensor 2

P0139, P0157

Heated oxygen sensor 2

P1146, P1166

Heated oxygen sensor 2

P1147, P1167

HO2S HEATER

Heated oxygen sensor 1 heater

P0031, P0032, P0051,
P0052

Heated oxygen sensor 2 heater

P0037, P0038, P0057,
P0058

EGR SYSTEM

EGR function

P0400

EGRC-BPT valve function

P0402

EGR function

P1402

Self-diagnosis result

Example

Diagnosis

Ignition

OFF – ON –

OFF

Ignition

OFF – ON –

OFF

Ignition

OFF – ON –

OFF

Ignition

OFF – ON – OFF

All OK

Case 1

P0400

OK (1)

– (1)

OK (2)

– (2)

P0402

OK (1)

– (1)

OK (2)

P1402

OK (1)

OK (2)

– (2)

SRT of EGR

“CMPLT”

Case 2

P0400

OK (1)

– (1)

P0402

– (0)

OK (1)

– (1)

P1402

OK (1)

OK (2)

– (2)

SRT of EGR

“INCMP”

“CMPLT”

NG exists

Case 3

P0400

–

P0402

–

P1402

–

NG (Consecu-

tive NG)

(1st trip) DTC

1st trip DTC

–

1st trip DTC

DTC (=MIL “ON”)

SRT of EGR

“INCMP”

“CMPLT”

EC-626

[VG33E]

ON BOARD DIAGNOSTIC (OBD) SYSTEM

When all SRT related self-diagnoses showed OK results in a same cycle (Ignition OFF – ON – OFF), the SRT
will indicate “CMPLT”.

→ Case 1 above

When all SRT related self-diagnoses show OK results through several different cycles, the SRT will indicate
“CMPLT” 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 “CMPLT”.

→ Case 3 above

The table above shows that the minimum number of cycles for setting SRT as “INCMP” is one (1) for each
self-diagnosis (Case 1 and 2) or two (2) for one self-diagnosis (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 “CMPLT” at the time the respective self-diagnoses have one (1) OK result.

●

The emissions inspection requires “CMPLT” of the SRT only with OK self-diagnosis result.

●

When, during SRT driving pattern, 1st trip DTC (NG) is detected prior to “CMPLT” of SRT, the self-diagno-
sis memory must be erased from ECM after repair.

●

If the 1st trip DTC is erased, all the SRT will indicate “INCMP”.

NOTE:
SRT can be set as “CMPLT” together with the DTC(s). Therefore, DTC check must always be carried out prior
to the State emission inspection even though the SRT indicates “CMPLT”.

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