With Manufacturer's Scan Tool

Oxygen Sensor (O2S) Heater 1 -Z29- Behind Three Way Catalytic Converter (TWC), Checking







Special tools and workshop equipment required
- V.A.G 1526 A Multimeter
- V.A.G 1594 A Connector test kit
- V.A.G 1598/31 Text box

Requirements
- Coolant temperature at least 80 degrees C.
- Fuse for Oxygen Sensor (O2S) heating OK.

Work sequence







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

NOTE:







To gain access to the connector, remove coolant expansion tank bolt (arrow) and move expansion tank to side. Fuel hoses remain connected.







- 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 Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-.

If specified value is obtained:







- Connect multimeter between terminals -1- (B+) and -2- (Ground) 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 the 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 ECM.







- 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).