Oxygen Sensor (O2S) Heater -Z19- For Oxygen Sensor Before Three Way Catalytic Converter (TWC), Checking

Oxygen Sensor (O2S) Heater -Z19- For Oxygen Sensor Before 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 Test box

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

Work sequence







- Disconnect 6-pin connector (black) -5- to Oxygen Sensor before Three Way Catalytic Converter (TWC).








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 3 and 4 to measure resistance.
- Specified value at room temperature 2.5 to 10 Ohms

If specified value is not obtained:
- Replace Heated Oxygen Sensor (HO2S) -G39-.

If specified value is obtained:

Checking voltage supply for Oxygen Sensor heating







- Connect multimeter between terminals 3 and 4 to measure voltage.
- Start engine.
- Specified value: approx. battery voltage (B+)

NOTE: Points at which Oxygen Sensor 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 zone 2.

If no voltage is present:







- Connect multimeter as follows to measure voltage.

Connector Terminal Measure to
3 Engine Ground (GND)

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

If no voltage is present:

Check wiring from terminal 3 on the connector via the 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
4 (engine control module Battery positive (B+)
ground activation)

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

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 2.

- Switch ignition off.

If no voltage is present:
- Connect test box V.A.G 1598/31 to wiring harness for engine control module; do not connect directly to Engine Control Module (ECM).







- Check for open circuit in following wiring connections:

Connector Test box V.A.G 1598/31
terminal Socket
4 5

- Repair open circuit, if necessary.

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