With Manufacturer's Scan Tool

Oxygen Sensor (O2S) Heating -Z29- For Oxygen Sensor After Three Way Catalytic Converter (TWC), Checking

Special tools and equipment







- V.A.G 1526 A Multimeter
- V.A.G 1594 A Connector test kit
- V.A.G 1598/31 Text box

Test requirements:
- Coolant temperature at least 80 degree C.
- Fuse for Oxygen Sensor (O2S) heating OK.

Test sequence
- Unscrew the protective cover -2- (arrow).







- Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) -G130-.







- Connect multimeter between terminals -1- and -2- to measure resistance.
- Specified value at room temperature 6.4 to 47.5 Ohm

If specified value is not obtained:
- Replace Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130-.

If specified value is obtained:
- Check voltage supply for oxygen sensor heating

Voltage Supply for Oxygen Sensor Heating







- Connect multimeter between terminals -1- (positive (B+)) and -2- (ground (GND)) to measure voltage.
- Start engine.
- Specified value: approx. battery voltage (B+)

NOTE: Points at which Oxygen Sensor (O2S) heating is switched on and off by Engine Control Module (ECM) can be observed in "Reading measured value block" function, display group number 041 and display field 4.

If no voltage is present:







- Connect multimeter as follows to measure voltage:

Connector terminal Measure to
1 Engine ground (GND)

- Operate starter briefly.
- Specified value: approx. battery voltage (B+)

If no voltage is present again:
- Check wire connection from connector terminal 1 via fuse to fuel pump relay for open circuit:

If voltage supply is OK:







- Connect multimeter as follows to measure voltage:

Connector terminal Measure to
2 (ground activation by ECM) Battery positive (B+)

- Start engine.
- Specified value: approx. battery voltage (B+), voltage may fluctuate

If no voltage is present:
- Connect test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect to the ECM. Electrical Testing Using VAG1598/31 Test Box







- Check for open circuit in the following wiring connections:

Connector terminal Test box V.A.G 1598/31
Socket
2 63

- Repair open circuit, if necessary.

If wiring is OK but there is no ground (GND) supply for the Oxygen Sensor
(O2S) heating:
- Replace Engine Control Module (ECM).