Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
For circuit wiring diagram, see Figure
or Figure
. For connector identification and locations, see CONNECTOR IDENTIFICATION
.
- Retighten Ground Screws
Turn ignition off. Loosen and retighten engine ground screws. See Figure . Go to next step. - Retighten HO2S1
Turn ignition off. Loosen and retighten appropriate HO2S1 to 30-44 ft. lbs. (40-60 N.m). See Figure . Go to next step. - Check For Exhaust Leak
Start engine and let it idle. Listen for exhaust leak before 3-way catalyst. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step. - Check For Intake Leak
Listen for intake air leak after MAF sensor. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step. - Clear Self-Learning Data
Start engine and warm to normal operating temperature.With CONSULT-II
- Select SELF-LEARNING CONT in WORK SUPPORT mode with CONSULT-II.
- Clear self-learning control coefficient by pressing CLEAR or START.
Without CONSULT-II
- Turn ignition off. Disconnect MAF sensor harness connector. See Figure .
- Start engine and let it idle for at least 3 seconds. Stop engine.
- Reconnect MAF sensor. Ensure 1st trip DTC P0102 is displayed. Clear 1st trip DTC.
Run engine for at least 10 minutes at idle speed. If 1st trip DTC P0171, P0172, P0174 or P0175 is detected and engine is difficult to start, perform diagnosis for DTC P0171, P0172, P0174 or P0175. See DTC P0171 OR DTC P0174 . If 1st trip DTC P0171, P0172, P0174 or P0175 is not detected and engine is not difficult to start, go to next step.
- Check Input Signal Circuit
Disconnect ECM harness connector. See Figure . Check continuity between HO2S1 harness connector terminal No. 2 and ECM harness connector terminal No. 94 (on bank 1) or No. 62 (on bank 2). See Figure or Figure . Continuity should exist. Also, check harness for short to ground and short to power. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step. - Check Ground Circuit
Check continuity between engine ground and HO2S1 harness connector terminal No. 4 (Black wire). Continuity should exist. Also, check harness for short to power. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST to verify repair. If problem is not found, go to next step. - Check HO2S1 Heater
Measure resistance between HO2S2 terminals No. 2 and 3. See Figure . Resistance should be 2.3-4.3 ohms at 77°F (25°C). Check continuity between HO2S1 terminal No. 1 and terminals No. 2, 3 and 4. Continuity should not exist. Also, check continuity between HO2S1 terminal No. 4 and terminals No. 1, 2 and 3. Continuity should not exist. If HO2S1 tests as specified, go to next step. If HO2S1 does not test as specified, replace HO2S1. Perform DTC CONFIRMATION TEST to verify repair. - Check HO2S1
Reconnect all harness connectors. Start engine and warm to normal operating temperature.With CONSULT-II
- Select MANU TRIG, and adjust TRIGGER POINT to 100% in DATA MONITOR mode with CONSULT-II. Select HO2S1 (B1)/(B2) and HO2S1 MNTR (B1)/(B2). Hold engine speed at 2000 RPM. Press RECORD. The following should occur:
- HO2S1 MNTR (B1)/(B2) changes from RICH to LEAN to RICH 5 times in 10 seconds.
- HO2S1 (B1)/(B2) voltage goes above 0.6V at least once.
- HO2S1 (B1)/(B2) voltage goes below 0.3V at least once.
- HO2S1 (B1)/(B2) voltage never exceeds 1.0V.
Without CONSULT-II
- Measure voltage between ground and ECM terminal No. 94 (bank 1) or No. 62 (bank 2) by backprobing. Increase engine speed to 2000 RPM. The following should occur:
- Voltage should cycle from less than .3 volt to more than .6 volt and back more than 5 times within 10 seconds.
- Maximum voltage should be more than .6 volt at least once.
- Minimum voltage should be less than .3 volt at least once.
- Voltage should never exceed one volt.
If operation is as specified, go to next step. If operation is not as specified, replace HO2S1. Perform DTC CONFIRMATION TEST to verify repair.
- Select MANU TRIG, and adjust TRIGGER POINT to 100% in DATA MONITOR mode with CONSULT-II. Select HO2S1 (B1)/(B2) and HO2S1 MNTR (B1)/(B2). Hold engine speed at 2000 RPM. Press RECORD. The following should occur:
- Check MAF Sensor
Reconnect all harness connectors. Start engine and warm to normal operating temperature. Check MAF sensor as shown in illustration. See Figure . If MAF sensor is okay, go to next step. If MAF sensor is not okay, replace MAF sensor. Perform DTC CONFIRMATION TEST to verify repair. - Check PCV Valve
With engine idling, remove PCV valve from valve cover. A properly working valve makes a hissing noise as air passes through it. A strong vacuum should be felt immediately when a finger is placed over valve inlet. If operation is as specified, go to next step. If operation is not as specified, replace PCV valve. Perform DTC CONFIRMATION TEST to verify repair. - Check For Intermittent
Check for intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Perform DTC CONFIRMATION TEST to verify repair.