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).