Oxygen Sensor Heating Relay

TEST PROCEDURE:

Status Monitoring:
Voltage for oxygen sensor heating is supplied via the Fuel Pump Relay (EKP).
Activation is only possible at the relay for cylinders 1-6 (the relay supplies both sensor heaters) and takes place at one second intervals. The relay remains switched on during normal operation until high engine speeds or load occur.

Possible Causes for Defect:
- Wire to Digital Motor Electronic (DME) control unit Pin 23 defective.
- Relay or voltage supply not OK.
- Fuse 28 defective.