DTC P0135, P0141, P0155 Or P0161 - Fuel Control: Condition

DTC P0135 or P0141 received separately indicate a short to ground or open in HO2S heater circuit. DTCs received in pairs, with one downstream heater code and one upstream heater code, are treated as the following separate codes.

• DTC P0135 for right front HO2S.
• DTC P0155 for left front HO2S.
• DTC P0141 for right rear HO2S.
• DTC P0161 for left rear HO2S.

Possible causes are as follows:

• Signal shorted in wiring harness or HO2S.
• Water in connectors.
• Cut or pulled wires.
• Open in PWR GND or VPWR circuit.

1) Check HO2S Heater Signal Circuit  Inspect HO2S connectors for damage or poor connection. Repair or replace connectors as necessary. If HO2S connectors are okay, go to next step.

2) Perform KOEO Self-Test  Start engine and operate at 2000 RPM for 5 minutes. Turn ignition off. Perform KOEO self-test. If DTC P0135, P0141 or P0155 are present, go to next step. If specified DTCs are not present, go to CIRCUIT TEST Z (INTERMITTENT).

3) Check For Voltage At HO2S Heater Wiring Harness Connector  Turn ignition off. Disconnect suspect HO2S. Inspect wiring harness for damage and repair as necessary. Turn ignition on. Measure voltage between SIG RTN and VPWR terminal at HO2S wiring harness connector. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, go to step 5).

4)  Turn ignition off. With suspect sensor disconnected, measure resistance between VPWR terminal at HO2S wiring harness connector and test pins No. 71 and 97 at breakout box. If resistance is less than 4 ohms, go to next step. If resistance is 4 ohms or more, check circuit fuse. If fuse is okay, repair open circuit and repeat QUICK TEST.

5) Check HO2S Heater Resistance  Turn ignition off. With suspect sensor disconnected, measure resistance between HO2S HEATER GND terminal and VPWR terminal at HO2S wiring harness connector. If resistance is 3-30 ohms, go to next step. If resistance is not 3-30 ohms, replace HO2S sensor and repeat QUICK TEST.

6)  Leave ignition off and suspect sensor disconnected. Measure resistance between HO2S HEATER GND terminal at HO2S wiring harness connector and HO2S case. Measure resistance between HO2S HEATER GND terminal and SIG RTN terminal at HO2S wiring harness connector. Measure resistance between VPWR terminal at HO2S wiring harness connector and HO2S case. If each resistance measurement is more than 10,000 ohms, go to next step. If any resistance is 10,000 ohms or less, replace HO2S and repeat QUICK TEST.

7) Check For Short Circuit  Leave ignition off and sensor disconnected. Disconnect scan tool from DLC (if applicable). Disconnect PCM 104-pin connector. Inspect connector for damage and repair if necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between suspect sensor and test pins indicated as follows:

• DTC P0135 (RF), test pin No. 93 and test pins No. 24, 76, 91, 97 and 103.
• DTC P0141 (RR), test pin No. 95 and test pins No. 24, 76, 91, 97 and 103.
• DTC P0155 (LR), test pin No. 94 and test pins No. 24, 91, 97 and 103.
• DTC P0161 (LR), test pin No. 96 and test pins No. 24, 91, 97 and 103.

If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short in circuit and repeat QUICK TEST.

8) Check For Open HO2S Heater Ground Harness Circuit  Leave ignition off and sensor disconnected. Measure resistance between HO2S HEATER GND terminal at HO2S wiring harness connector and appropriate test pin as follows:

• Right front (or front) HO2S sensor; test pin No. 93.
• Left front (or rear on 4.9L) HO2S sensor; test pin No. 94.
• Right rear (or rear) HO2S sensor; test pin No. 95.
• Left rear HO2S sensor; test pin No. 96.

If resistance is 4 ohms or more, repair open circuit or excessive resistance in wiring harness and repeat QUICK TEST. If resistance is less than 4 ohms, replace PCM and repeat QUICK TEST.