P305D

2A66 - P305D

Information saved in
DME

Fault code
2A66 - P305D

Fault text
Oxygen sensor heating before catalytic converter, function

Fault description
Pre-catalyst oxygen sensor heater, operation

Condition for fault identification
Test condition:
Engine running
Terminal condition: none
Voltage condition:
10.7 V < electrical system voltage from main relay ubrsq <
16 V

Condition for fault memory entry
3 sec.

Action in service
- Check oxygen sensor heater (3.5 ohms resistance in the
heater wire at room temperature): Excessive contact
resistance at plugs and in wire (DME - wiring harness -
sensor) If the resistance varies from spec. by more than 1
ohm replace the post-catalyst oxygen sensor
- Check plug-in connections
- Check wiring harness between oxygen sensor and DME

Fault effect and breakdown warning
None
MIL lights up when fault is detected in two consecutive
driving cycles

Driver information
Warning light:
MIL ON

Service instruction
None