P0135

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

NOTE: Information marked with an asterisk (*) applies to DTC P0141.

1. Reset the PCM.
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), the secondary HO2S (Sensor 2), and the PCM.

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 5.6 Ohms (about 13 Ohms)* ?

YES - Go to step 6.

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





6. Check for 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. At the wire harness side, 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 PCM connector C (31P) (PCM connector A, 32P) *.





11. Check for continuity between PCM connector terminal C1 (A8) * and body ground.

Is there continuity?

YES - Repair short in the wire between the PCM (C1, A8 *) and the HO2S (primary or secondary *) (Sensor 1, Sensor 2 *).

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





12. At the wire harness side, measure voltage between HO2S 4P connector terminal No.4 and body ground.

Is there battery voltage?

YES - Go to step 13.

NO - Check the No.6 ECU (PCM) CRUISE CONTROL (15 A) fuse in the driver's under-dash fuse/relay box. If the fuse is OK, repair open in the wire between the primary HO2S (Sensor 1) (secondary HO2S (Sensor 2)) * and the No.6 ECU (PCM) CRUISE CONTROL (15 A) fuse.

13. Turn the ignition switch OFF.
14. Reconnect the HO2S (primary or secondary *) (Sensor 1, Sensor 2 * ) 4P connector.
15. Disconnect PCM connector C (31P) (PCM connector A, 32P) *.
16. Turn the ignition switch ON (II).





17. Measure voltage between PCM connector terminal C1 (A8) * and B2.

Is there 0.1 V or less?

YES - Repair open in the wire between the PCM (C1, A8 *) and the HO2S (primary or secondary *) (Sensor 1, Sensor2 *).

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