P0141

DTC P0135: Primary HO2S (Sensor 1) Heater Circuit Malfunction

DTC P0141: Secondary HO2S (Sensor 2) Heater Circuit Malfunction

NOTE:
- Information marked with an asterisk (*) applies to DTC P0141.
- Before you troubleshoot, record all freeze data and review the general troubleshooting information.

1. Reset the ECM.
2. Start the engine.

Is DTC P0135 or P0141 indicated?

YES - Go to step 3.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the primary HO2S (Sensor 1) or secondary HO2S (Sensor 2) and at the ECM.

3. Turn the ignition switch OFF.
4. Disconnect the HO2S (primary or secondary*) (Sensor 1 or Sensor 2*) 4P connector.




5. At the HO2S side, measure resistance between HO2S 4P connector terminals No. 3 and No. 4.

Is there about 3.3 Ohm (12 - 14.3 Ohm)?

YES - Go to step 6.

NO - Replace the primary HO2S (Sensor 1) or secondary HO2S (Sensor 2)*.




6. At the HO2S side, check continuity between body ground and HO2S 4P connector terminals No. 3 and No. 4 individually.

Is there continuity?

YES - Replace the primary HO2S (Sensor 1) or secondary HO2S (Sensor 2)*.

NO - Go to step 7.

7. Turn the ignition switch ON (II).




8. Measure voltage between HO2S 4P connector terminals No. 3 and No. 4.

Is there battery voltage?

YES - Go to step 9.

NO - Go to step 12.

9. Turn the ignition switch OFF.
10. Disconnect ECM connector C (31P).




11. Check for continuity between ECM connector terminal C1 (C11)* and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM (C1, C11*) and the HO2S (primary or secondary*) (Sensor 1 or Sensor 2*).

NO - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.




12. Measure voltage between primary HO2S 4P connector terminal No. 3 (secondary HO2S No. 4)* and body ground.

Is there battery voltage?

YES - Go to step 13.

NO - Repair open in the wire between the primary HO2S (Sensor 1), the secondary HO2S (Sensor 2)* and the No. 6 ACG (15 A) fuse.

13. Turn the ignition switch OFF.
14. Reconnect the HO2S 4P connector.
15. Disconnect ECM connector C (31P).
16. Turn the ignition switch ON (II).




17. Measure voltage between ECM connector terminals B2 and C1 (B2 and C11)*.

Is there 0.1 V or less?

YES - Repair open in the wire between the ECM (C1 and C11*) and the HO2S (primary or secondary*) (Sensor 1 or Sensor 2*).

NO - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.