Heater, Check
Oxygen Sensors Behind Catalytic Converter, Checking Heating
Special tools and equipment
- VAG 1526 A
- VAG 1594 A
- VAG 1598/31
Test requirements
- Fuse for oxygen sensor heating OK.
Test sequence
- Disconnect 4-pin connector of relevant oxygen sensor behind catalytic converter.
- Connect multimeter between terminals 1 and 2 to measure resistance.
- Specified value at room temperature 6.4 to 47.5 Ohms
If specified value is not obtained:
- Replace relevant oxygen sensor behind catalytic converter.
If specified value is obtained:
Check voltage supply for oxygen sensor heating
- Connect multimeter between terminals 1 (positive) and 2 (Ground) to measure voltage.
- Start engine.
- Specified value: approx. battery voltage.
NOTE: Points at which oxygen sensor heating is switched on and off by engine control module can be observed in "Reading measured value block" function, display group number 041 and display zone 4.
If no voltage is present:
- Connect multimeter as follows to measure voltage:
Connector Measure to
terminal
1 Engine ground
- Operate starter briefly.
- Specified value: approx. battery voltage.
If no voltage is present:
- Check wiring from terminal 1 on connector via fuse to fuel pump relay for an open circuit.
If voltage supply is OK:
- Connect multimeter as follows to measure voltage:
Connector Measure to
terminal
2 (ground activation by Battery positive
engine control module)
- Start engine.
- Specified value: approx. battery voltage, may fluctuate.
- Switch ignition off.
If no voltage is present:
- Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. Wiring and Component Testing Using VAG1598/31 Test Box
- Check for open circuit in following wiring connections:
- Oxygen sensor (O2S) heater 1 -Z29- Bank 1 behind Cat:
Connector Test box VAG 1598/31
terminal Socket
2 63
- Oxygen Sensor (O2S) heater 2 -Z30- Bank 2 behind Cat:
Connector Test box VAG 1598/31
terminal Socket
2 6
- Repair open circuit, if necessary.
If wiring is OK but there is no Ground supply for oxygen sensor heater:
- Replace engine control module.