Sensor and Sensor Control Check

Oxygen Sensor Control After Three Way Catalytic Converter (TWC), Checking

Display on VAS 5051:







1 - Enter display group.
- Enter "037" for "display group number 037" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:







- Activate basic setting by pressing -A- button.
- Check Oxygen Sensor (O2S) voltage in display field -2-.
- Check Oxygen Sensor (O2S) correction value in display field-3- and diagnosis result in display field -4-.

Display Group 037:

Evaluating display group 037

Display Field 2:

Continuation

If specification in display field 3 or 4 is not obtained:
- Perform test drive to free Oxygen Sensor (O2S) from any possible residues and repeat test.

If specified value in display field 3 or 4 is not obtained, even after a test drive has been performed:
- Replace Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC).

NOTE: If the Oxygen Sensor (O2S) voltage is OK and after a road test the Oxygen Sensor correction value is still outside the specification, this indicates aging of the Oxygen Sensor before the Three Way Catalytic Converter (TWC).

Checking basic voltage







- Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) 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 voltage.
- Switch ignition on.
- Specified value: 0.400...0.500 V
- Switch ignition off.

If the specified value is obtained:
- Replace Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130-.

If the specified value is not obtained:







- Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) -G39-.







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

- Connect test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect Engine Control Module (ECM). Wiring and Component Testing Using VAG1598/31 Test Box







- Test for open circuit in following wiring connections.

Connector terminal Test box VAG 1598/31 Socket

3 68
4 69

- Repair open circuit, if necessary.
- Check for shorts between two wires.

If the wiring is OK:
- Replace Engine Control Module (ECM).