DTC 1-5-3 Rear Heated Oxygen Sensor Signal

1-5-3 REAR HEATED OXYGEN SENSOR SIGNAL

Preconditions for DTC
^ In order for the Rear Heated Oxygen Sensor (HO2S) to be able to affect the fuel trim and monitor the Three-Way Converter (TWC) and front HO2S, it must be at operating temperature and at the correct output voltage. Monitoring of the HO2S function begins approx. 3 minutes after the HO2S preheating phase begins. If there is a fault with the front or rear HO2S or their leads, so that the output voltage from the rear HO2S differs from the permitted value, DTC 1-5-3 is set.

Substitute value
^ Fuel trim is inhibited.
^ TWC diagnosis is inhibited.

Fault sources
^ Signal too high:
- Signal lead (+) short circuited to voltage supply.
- Signal lead (-) short circuited to voltage supply.
- Defective front HO2S.
- Defective rear HO2S.

^ Signal too low:
- Signal lead (+) short circuited to ground.
- Signal lead (-) short circuited to ground.
- Break in signal lead (+).
- Break in signal lead (-).
- Defective front HO2S.
- Defective rear HO2S.

^ Faulty signal:
- Signal lead (+) short circuited to signal lead (-).
- Defective rear HO2S.

Fault symptom
^ None.