Oxygen Sensor (O2S) and Oxygen Sensor Control Before Three Way Catalytic Converter (TWC), Checking
Oxygen Sensor (O2S) and Oxygen Sensor control before catalytic converter, 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.
- VAS 5051.
- VAS 5051/1 Adapter.
Test requirements:
- No leaks in exhaust system.
- Coolant temperature at least 80 degree C.
Test sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" in selection. Engine must be run at idle speed. Connecting VAS 5051 Scan Tool
Display on VAS 5051:
- Under -1- select diagnostic function "04 - Basic setting".
Display on VAS 5051:
1 - Enter display group.
- Enter "030" for "display group number 030" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Activate basic setting by pressing -A- button.
- Check specification in display field -1-.
NOTE:
- By increasing the engine speed the specified values are achieved more quickly.
- The "Oxygen Sensor status" indicates the condition of the Oxygen Sensor control and the Oxygen Sensor (O2S).
Display Group 030:
Display Field 1 - 2:
Display on VAS 5051:
- Only continue test if display in display field -1- has reached "111" at least once.
- Press <- button.
Checking Oxygen Sensor (O2S) adaptation values and Oxygen Sensor (O2S) control
Display on VAS 5051:
1 - Enter display group.
- Enter "032" for "display group number 032" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Activate basic setting by pressing -A- button.
- Check indication in display groups -1- and -2-.
Display Group 032:
- Press <- button.
Display on VAS 5051:
1 - Enter display group.
- Enter "033" for "display group number 033" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Activate basic setting by pressing -A- button.
- Check indication in display groups -1-and -2-.
Display Group 033:
Continuation
If the specified result is not obtained in display field, or if the value does not fluctuate by at least 2%:
- Perform test drive to free Oxygen Sensor (O2S) from any possible residues and repeat test.
If the specified result is not obtained in display field 1 3, or if the value does not fluctuate by at least 2%, even after the test drive:
- Check basic voltage.
- Check Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) heating.
- Check Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) aging.
Evaluating display group 032
Display Field 1 - 2:
Evaluating display group 032
Display Field 1 - 2:
Evaluating display group 033
Display Field 2:
Checking basic voltage
- Disconnect 6-pin connector (black) -5- 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 1 and 5 to measure voltage.
- Switch ignition on.
- Specified value: 0.400...0.500 V
- Switch ignition off.
If specified value is not obtained:
- Check Oxygen Sensor (O2S) wiring.
If specified value is obtained:
- Replace Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC).
Checking Oxygen Sensor (O2S) wiring
- Disconnect 6-pin connector (black) -5- 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 test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect Engine Control Module (ECM).
- Test for open circuit in the following wiring connections.
Connector terminal Test box VAG 1598/31 Socket
1 70
2 71
5 51
6 52
- Repair open circuit, if necessary.
- Check for shorts between two wires.
If the wiring is OK:
- Replace Engine Control Module (ECM).