Heater Check

Oxygen Sensor Heating, Oxygen Sensor (O2S) Heater 1-Z29- After Catalytic Converter, Checking

Special Tools and Equipment







- VAG1526A
- VAG1594A
- VAG1598/31


Test requirements:
- Coolant Temperature at least 80 °C.
- Fuse for oxygen sensor heating OK

Test sequence







- Disconnect 4-pin harness connector -1- (brown) to Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC) - G130-.


NOTE: Coolant reservoir screws must be removed and coolant reservoir must be placed to side in order to access the harness connector. The coolant hoses can remain connected.







- Connect multimeter between terminal 1 and 2 for resistance measurement.
- 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:
- Check voltage supply of oxygen sensor heating.

Checking voltage supply for oxygen sensor heating







- Connect multimeter between terminal 1 (B+) and 2 (Ground -GND-) for voltage measurement.
- Start engine.
- Specification: approx. battery voltage


NOTE: When the Engine Control Module (ECM) switches oxygen sensor heating on and off, it may be observed via the function "read measuring value block", in display group number 041 display field 4.


If there is no voltage:
- Connect multimeter for voltage measurement as follows:

Harness connector Measure to
Terminal

1(B+) Vehicle Ground (GND)


- Operate starter briefly.
- Specification: approx. battery voltage

If there is no voltage again:
- Check wire connection from terminal 1 of connector to Fuel Pump (FP) relay via fuse for open circuit:

If voltage supply is OK:







- Connect multimeter for voltage measurement as follows:







- Start engine.
- Specification: approx. battery voltage, possibly fluctuating
- Switch ignition off.

If there is no voltage:
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM.







- Check the following wire connection for open circuit:

Harness connector VAG1598/31 test box
Terminal Socket

2 63

- Repair open circuit if necessary.

If wire connection is OK, but there is no Ground (GND) supply for oxygen sensor heating:
- Replace Engine Control Module (ECM).