Diagnostic Procedure

Check Ground Connections
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.
Retighten Air Fuel Ratio (A/F) Sensor 1
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)
2. Go to 3.
Clear The Self-learning Data .
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.
4. Run engine for at least 10 minutes at idle speed.
  Is the 1st trip DTC P0171 or P0174 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 or P0174 detected?
  
  Is it difficult to start engine?
  
  Yes or No
  1. Yes: Perform trouble diagnosis for DTC P0171 or P0174. Refer to DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION .
  2. No: Go to 4.
Check Air Fuel Ratio (A/F) Sensor 1 Power Supply Circuit
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 6.
  2. NG: Go to 5.
Detect Malfunctioning Part
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.
Check Air Fuel Ratio (A/F) Sensor 1 Input Signal Circuit
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 7.
  2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
Check Air Fuel Ratio (A/F) Sensor 1 Heater
Refer to COMPONENT INSPECTION .

OK or NG
1. OK: Go to 8.
2. NG: Replace air fuel ratio (A/F) sensor 1.
Check Intermittent Incident
Perform TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

OK or NG
1. OK: Go to 9.
2. NG: Repair or replace.

CAUTION:

Discard any air fuel ratio (A/F) sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
Before installing new air fuel ratio (A/F) sensor, clean exhaust system threads using Heated Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
1. Inspection end

Replace Air Fuel Ratio (A/F) Sensor 1
Replace air fuel ratio (A/F) sensor 1.