Diagnostic Procedure

1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. See Figure. Refer to GROUND INSPECTION .

OK or NG

1. OK: Go to 2.
2. NG: Repair or replace ground connections.

Loosen and retighten the air fuel ratio (A/F) sensor 1. See Figure.

1. Tightening torque: 40 - 60 N-m (4.1 - 6.1 kg-m, 30 - 44 ft-lb) 

1. Go to 3.

1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst 1. See Figure.

OK or NG

1. OK: Go to 4.
2. NG: Repair or replace.

Listen for an intake air leak after the mass air flow sensor.

OK or NG

1. OK: Go to 5.
2. NG: Repair or replace.

With CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Select SELF-LEARNING CONT in WORK SUPPORT mode with CONSULT-II. See Figure.
3. Clear the self-learning control coefficient by touching CLEAR or START.
4. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171, P172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

Without CONSULT-II 

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector. See Figure.
4. Restart engine and let it idle for at least 3 seconds.
5. Stop engine and reconnect mass air flow sensor harness connector.
6. Make sure DTC P0102 is displayed.
7. Erase the DTC memory. Refer to HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION .
8. Make sure DTC P0000 is displayed.
9. Run engine for at least 10 minutes at idle speed.

   Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

   Is it difficult to start engine? 

Yes or No

1. Yes: Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION  or DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION .
2. No: Go to 6.

1. Turn ignition switch OFF.
2. Disconnect air fuel ratio (A/F) sensor 1 harness connector. See Figure.
3. Turn ignition switch ON.
4. Check voltage between air fuel ratio (A/F) sensor 1 terminal 3 and ground with CONSULT-II or tester. See Figure.
   1. Voltage: Battery voltage 

OK or NG

1. OK: Go to 8.
2. NG: Go to 7.

Check the following.

• Harness connectors E18, F48
• Fuse block (J/B) connector E201
• 10A fuse
• Harness for open or short between air fuel ratio (A/F) sensor 1 and fuse

1. Repair or replace harness or connectors.

1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between the following terminals. See Figure.

   Refer to wiring diagram. See WIRING DIAGRAM .

   1. Continuity should exist  .
4. Check harness continuity between the following terminals and ground. See Figure.

   Refer to wiring diagram. See WIRING DIAGRAM .

   1. Continuity should not exist  .
5. Also check harness for short to ground and short to power.

OK or NG

1. OK: Go to 9.
2. NG: Repair open circuit or short to ground or short to power in harness or connectors.

Refer to COMPONENT INSPECTION .

OK or NG

1. OK: Go to 10.
2. NG: Replace air fuel ratio (A/F) sensor 1.

Refer to COMPONENT INSPECTION .

OK or NG

1. OK: Go to 11.
2. NG: Replace mass air flow sensor.

Refer to POSITIVE CRANKCASE VENTILATION .

OK or NG

1. OK: Go to 12.
2. NG: Repair or replace PCV valve.

Perform TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

OK or NG

1. OK: Go to 13.
2. NG: Repair or replace.

Replace air fuel ratio (A/F) sensor 1.

1. Inspection end