Symptom: The MIL illuminates with one of the following DTCs:
* P0134 (air/fuel ratio sensor 1; heater system malfunction).
* P0135 (air/fuel ratio sensor 1; heater circuit malfunction).
* P0171 (fuel system too lean).
* P1157 (air/fuel ratio sensor 1; AFS circuit high voltage).
Probable cause: Under-hood temperature causes grease from an under-hood fuse box connector to melt, travel down through the engine wire harness, and drip onto the A/F sensor 4P connector.
* 2WD (USA produced) from VIN 5J6RE38….9L000001 thru 5J6RE38….9L015846
* 4WD (USA produced) from VIN 5J6RE48….9L000001 thru 5J6RE48….9L033733
* 2WD (Japan produced) from VIN JHLRE38….9C000001 thru JHLRE38….9C012601
* 4WD (Japan produced) from VIN JHLRE48….9C000001 thru JHLRE48….9C012830
* 2WD (Mexico produced) from VIN 3CZRE38….9G700001 thru 3CZRE38….9G703604
* 4WD (Mexico produced) from VIN 3CZRE48….9G700001 thru 3CZRE48….9G700902
Replace the A/F sensor and install a subharness kit.
A/F sensor P/N 36531-RZA-003, H/C 8404519
Subharness kit P/N 06322-SWA-305, H/C 9050097
1. Open the hood and locate the right branch of the engine harness (attached to the right side frame rail), near the power steering feed hose. Detach the engine harness from the frame rail by cutting through the harness body clip. Discard the clip.
2. Raise the vehicle on a lift.
3. Remove the A/F sensor. Disconnect the sensor with an O2 sensor wrench (Snap-On S3176 or equivalent). Discard the sensor.
4. Install a new A/F sensor and torque to 33 lb-ft (33 Nm). Do not connect the sensor’s 4P connector yet.
5. Disconnect the engine harness 4P connector from its clip.