Infiniti G20 (P11). Manual — part 238
5
CHECK EGR VOLUME CONTROL VALVE-II
With CONSULT-II
1. Remove EGR volume control valve.
2. Reconnect ECM harness connector and EGR volume control valve harness connector.
3. Turn ignition switch “ON”.
4. Perform “EGR VOL CONT/V” in “ACTIVE TEST” mode with CONSULT-II.
5. Check that EGR volume control valve shaft moves smoothy forward and backward according to the valve opening
steps.
SEF067Y
OK or NG
OK
©
GO TO 7.
NG
©
Replace EGR volume control valve.
6
CHECK EGR VOLUME CONTROL VALVE-II
Without CONSULT-II
1. Remove EGR volume control valve.
2. Reconnect ECM harness connector and EGR volume control valve harness connector.
3. Turn ignition switch “ON” and “OFF”.
4. Check that EGR volume control valve shaft moves smoothly forward and backward according to the ignition switch
position.
SEF560W
OK or NG
OK
©
GO TO 7.
NG
©
Replace EGR volume control valve.
7
CHECK INTERMITTENT INCIDENT
Refer to “TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT”, EC-146.
©
INSPECTION END
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DTC P0403 EGR VOLUME CONTROL VALVE (CIRCUIT)
Diagnostic Procedure (Cont’d)
EC-363
SEF484Y
On Board Diagnosis Logic
NCEC0240
The ECM monitors the switching frequency ratio of heated oxygen
sensor 1 (front) and 2 (rear).
A three way catalyst with high oxygen storage capacity will indicate
a low switching frequency of heated oxygen sensor 2 (rear). As
oxygen storage capacity decreases, the heated oxygen sensor 2
(rear) switching frequency will increase.
When the frequency ratio of heated oxygen sensor 1 (front) and 2
(rear) approaches a specified limit value, the three way catalyst
malfunction is diagnosed.
DTC No.
Malfunction is detected when ...
Check Items (Possible Cause)
P0420
I
Three way catalyst does not operate properly.
I
Three way catalyst does not have enough oxygen stor-
age capacity.
I
Three way catalyst
I
Exhaust tube
I
Intake air leaks
I
Injectors
I
Injector leaks
I
Spark plug
I
Improper ignition timing
SEF671Y
SEF672Y
SEF560X
DTC Confirmation Procedure
NCEC0241
NOTE:
If “DTC Confirmation Procedure” has been previously conducted,
always turn ignition switch “OFF” and wait at least 10 seconds
before conducting the next test.
WITH CONSULT-II
NCEC0241S01
TESTING CONDITION:
I
Open engine hood before conducting the following proce-
dure.
I
Do not hold engine speed for more than the specified
minutes below.
1)
Turn ignition switch “ON”.
2)
Select “DTC & SRT CONFIRMATION” then “SRT WORK SUP-
PORT” mode with CONSULT-II.
3)
Start engine.
4)
Rev engine up to 3,000
±
500 rpm and hold it for 3 consecutive
minutes then release the accelerator pedal completely.
5)
Wait 5 seconds at idle.
6)
Rev engine up to 2,500
±
500 rpm and maintain it until “INCMP”
of CATALYST changes to “CMPLT” (It will take approximately
5 minutes).
If not “CMPLT”, stop engine and cool it down to less than 70°C
(158°F) and then retest from step 1.
7)
Select “SELF-DIAG RESULTS” mode with CONSULT-II.
8)
Confirm that the 1st trip DTC is not detected.
If the 1st trip DTC is detected, go to “Diagnostic Procedure”,
EC-365.
DTC P0420 THREE WAY CATALYST FUNCTION
On Board Diagnosis Logic
EC-364
SEF074X
Overall Function Check
NCEC0242
Use this procedure to check the overall function of the three way
catalyst. During this check, a 1st trip DTC might not be confirmed.
With GST
1)
Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes.
2)
Stop vehicle with engine running.
3)
Set voltmeters probes between ECM terminals 62 [Heated
oxygen sensor 1 (front) signal], 63 [Heated oxygen sensor 2
(rear) signal] and engine ground.
4)
Keep engine speed at 2,000 rpm constant under no load.
5)
Make sure that the voltage switching frequency (high & low)
between ECM terminal 63 and engine ground is much less
than that of ECM terminal 62 and engine ground.
Switching frequency ratio = A/B
A: Heated oxygen sensor 2 (rear) voltage switching fre-
quency
B: Heated oxygen sensor 1 (front) voltage switching fre-
quency
This ratio should be less than 0.75.
If the ratio is greater than above, it means three way catalyst
does not operate properly.
NOTE:
If the voltage at terminal 62 does not switch periodically more
than 5 times within 10 seconds at step 4, perform trouble
diagnosis for DTC P0133 first. (See EC-217.)
Diagnostic Procedure
NCEC0243
1
CHECK EXHAUST SYSTEM
Visually check exhaust tubes and muffler for dent.
OK or NG
OK
©
GO TO 2.
NG
©
Repair or replace.
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DTC P0420 THREE WAY CATALYST FUNCTION
Overall Function Check
EC-365
2
CHECK EXHAUST AIR LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust air leak before the three way catalyst.
SEF099P
OK or NG
OK
©
GO TO 3.
NG
©
Repair or replace.
3
CHECK INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK
©
GO TO 4.
NG
©
Repair or replace.
4
CHECK IGNITION TIMING
Check for ignition timing.
Refer to “BASIC INSPECTION”, EC-107.
OK or NG
OK
©
GO TO 5.
NG
©
Adjust ignition timing.
5
CHECK INJECTORS
1. Refer to Wiring Diagram for Injectors, EC-597.
2. Stop engine and then turn ignition switch “ON”.
3. Check voltage between ECM terminals 101, 103, 105 and 107 and ground with CONSULT-II or tester.
SEF075X
Battery voltage should exist.
OK or NG
OK
©
GO TO 6.
NG
©
Perform “Diagnostic Procedure” INJECTOR, EC-598.
DTC P0420 THREE WAY CATALYST FUNCTION
Diagnostic Procedure (Cont’d)
EC-366
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