PGM-FI System

DTC Troubleshooting (cont'd)

11-535  

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

  1. Reset the ECM/PCM (see page 11-468).
  2. Start the engine.

Is the MIL on and does it indicate DTC 41?

YES

- Go to step 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.


  1. Turn the ignition switch OFF.
  2. Disconnect the primary HO2S (Sensor 1) 4P connector.
  3. At the primary HO2S side, measure resistance between the primary HO2S 4P connector terminals No. 3 and No. 4.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Wire side of female terminals

Is there 10-40 ohms?

YES

- Go to step 6.

NO

- Replace the primary HO2S (Sensor 1).


  1. Check for continuity between body ground and the primary HO2S 4P connector terminals No. 3 and No. 4 individually.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Wire side of female terminals

Is there continuity?

YES

- Replace the primary HO2S (Sensor 1).

NO

- Go to step 7.


  1. Turn the ignition switch ON (II).
  2. Measure voltage between the primary HO2S (Sensor 1) 4P connector terminal No. 3 and No. 4.

PRIMARY HO2S (SENSOR 1) 4P CONNECTOR

Terminal side of male terminals

Is there battery voltage?

YES

- Go to step 9.

NO

- Go to step 12.


  1. Turn the ignition switch OFF.
  2. Disconnect ECM/PCM connector A (31P).