DTC Troubleshooting: P0135 (41-2)

DTC P0135 (41-2):  Primary HO2S (Sensor 1) Heater Circuit Malfunction

1.Reset the ECM/PCM.

2.Start the engine.

Is DTC P0135 indicated?


YES - Go to 3.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the  primary HO2S (Sensor 1) and at the  ECM/ PCM.n


3.Turn the ignition switch OFF.

4.Disconnect the primary HO2S (Sensor 1) 4P connector.

5.Turn the ignition switch ON (II).

6.Measure voltage between primary HO2S (Sensor 1) 4P connector terminal No. 3 and body ground.

 

Is there battery voltage?


YES - Go to 8.


NO - Go to 7.

7.Check for continuity between body ground and primary HO2S (Sensor 1) 4P connector terminals No. 3.

 

Is there continuity?


YES - Repair short in the wire between the  primary HO2S (Sensor 1) and the No. 4 ACG (10A) fuse.n


NO - Check the No. 4 ACG (10A) fuse in the under-dash fuse/relay box. If the fuse is OK, repair open in the wire between the  primary HO2S (Sensor 1) and the No. 4 ACG (10A) fuse.n


8.Turn the ignition switch OFF.

9.Reconnect the primary HO2S (Sensor 1) 4P connector.

10.Disconnect the negative cable from the battery.

11.Disconnect ECM/PCM connector A (31P).

12.Reconnect the negative cable to the battery.

13.Turn the ignition switch ON (II).

14.Measure voltage between between body ground and ECM/PCM connector terminal A1.

 

Is there battery voltage?


YES - Go to 15.


NO - Repair open in the wire between  ECM/ PCM ( A1) and  primary HO2S (Sensor 1).n


15.Turn the ignition switch OFF.

16.Disconnect the primary HO2S (Sensor 1) 4P connector.

17.Check for continuity between body ground and ECM/PCM connector terminal A1.

 

Is there continuity?


YES - Repair short in the wire between the  ECM/ PCM (A1) and  primary HO2S (Sensor 1).n


NO - Go to 18.

18.Substitute a known-good primary HO2S (Sensor 1) and recheck.

Is DTC P0135 indicated?


YES - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away with a known-good  ECM/ PCM, replace the original ECM/PCM.n


NO - Replace the  primary HO2S (Sensor 1).n