Oxygen Sensor (O2S) Heater -Z19- (Before Catalytic Converter), Testing

Oxygen Sensor (O2S) Heater -Z19- (Before Catalytic Converter), Testing







Special tools and equipment
- VAG 1526 A
- VAG1594A
- VAG 1598/31

Requirements for test:
- Coolant temperature at least 80 degrees C
- Fuse for oxygen sensor heating OK

Test sequence







- Unbolt connector cover -arrows-.







- Unplug 6-pin connector -1- (black) for oxygen sensor (before catalytic converter) -G39.







- Connect multimeter (resistance measurement range) between contacts 3 and 4.

- Specification: 2.5 to 10 Ohms (at room temperature)

If the specification is not attained:
- Replace the heated oxygen sensor (HO2S) -G39-.

If the specification is obtained:
- Test voltage supply for oxygen sensor heating.

Testing voltage supply for oxygen sensor heating







- Connect multimeter (voltage measurement range) between contacts 3 and 4.
- Start the engine.

- Specification: approx. battery voltage


NOTE: If required, observe Display Group 041, display zone 2 in the "Read measured value block" function to find out when the engine control module is switching the oxygen sensor heating on and off.

If no voltage is present:







- Connect multimeter (voltage measurement range) as follows:

Connector Contact Measure against
3 (positive) Vehicle Ground

- Operate starter briefly.

- Specification: approx. battery voltage

If there is still no voltage reading:
- Test for open circuit in wiring connection between fuel pump relay and contact 3 on connector via fuse

If the voltage supply is OK:







- Connect multimeter (voltage measurement range) as follows:

Connector Contact Measure against
4 (switched Ground connection Battery positive
for engine control module)

- Start the engine.
- Specification: approx. battery voltage

NOTE: If required, observe Display Group 041, display zone 2 in the "Read measured value block" function to find out when the engine control module is switching the oxygen sensor heating on and off.

- Switch off ignition.

If no voltage is present:
- Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the engine control module itself. Scan Tool Testing and Procedures







- Test for open circuits in the following wiring connection:

Connector Contact Test box VAG 1598/31 Socket
4 5

- Correct any open circuits.

If the wiring connection is O.K. but the oxygen sensor heating still has no Ground connection:
- Install a new engine control module.