Oxygen Sensors Behind Catalytic Converter, Checking Heating
Oxygen Sensors Behind Catalytic Converter, Checking Heating
Special tools and equipment
- VAG1526 A
- VAG1594 A
- VAG1598/31
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 terminal Measure to
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 terminal Measure to
2 (ground activation by engine control module) Battery positive
- Start engine.
- Specified value: approx. battery voltage, may fluctuate
- Switch ignition off.
If no voltage is present:
- Connect test box VAG1598/31 to wiring harness for engine control module; do not connect engine control module.
- Check for open circuit in following wiring connections:
- Oxygen sensor (O2S) heater 1 -Z29- Bank 1 behind Cat:
Connector terminal Test box VAG1598/31 Socket
2 63
- Oxygen Sensor (O2S) heater 2 -Z30- Bank 2 behind Cat:
Connector terminal Test box VAG1598/31 Socket
2 6
- Repair open circuit, if necessary.
If wiring is OK but there is no Ground (GND) supply for oxygen sensor heater:
- Replace engine control module.