Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
- Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0136 and/or DTC P0156 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
- Check for open and short in wiring harness and electrical connectors between appropriate heated oxygen sensor on exhaust pipe and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor (bank No. 1 sensor No. 2) is located on driver's side exhaust pipe behind catalytic converter and heated oxygen sensor (bank No. 2 sensor No. 2) is located on passenger's side exhaust pipe behind catalytic converter. ECM is located behind glove box. See Figure. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
- With hand-held tester or scan tool still connected to DLC No. 3, start engine and warm engine to normal operating temperature. Increase engine speed to 2500 RPM for 3 minutes and then allow engine to idle. Monitor output voltage for appropriate heated oxygen sensor located on exhaust pipe behind catalytic converter while quickly accelerating engine to 4000 RPM 3 consecutive times. Output voltage should fluctuate from .40 volt or less to .50 volt or more. If output voltage is not within specification, replace appropriate heated oxygen sensor on exhaust pipe behind catalytic converter. See HEATED OXYGEN SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If output voltage is within specification, problem is intermittent. Check for defective connections or intermittent problem in wiring between appropriate heated oxygen sensor on exhaust pipe behind catalytic converter and ECM.