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, see Fig. 6 or, see Fig. 7.







- 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 VAG1598/31 to wiring harness for engine control module; do not connect engine control module. Wiring and Component Check With Test Box VAG 1598/31







- Check for open circuit in following wiring connections:

- Oxygen sensor (O2S) heater 1 -Z29- Bank 1 behind Cat:

Connector Test box VAG1598/31
terminal Socket
2 63

- Oxygen Sensor (O2S) heater 2 -Z30- Bank 2 behind Cat:

Connector Test box VAG1598/31
terminal 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.