Oxygen Sensor (O2S) and Oxygen Sensor Control Before Catalytic Converter, 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 Vehicle diagnostic, testing and information system
- VAS 5051/1 Adapter

Requirements
- No leaks in exhaust system
- Coolant temperature at least 80 degrees C.

Work 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.







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).










NOTE: The first digit of the 3-digit display (heating) fluctuates between 0 and 1.







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-.







- 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-.







Note on display field 2:
Displayed is the Oxygen Sensor (O2S) voltage signal which was prepared and smoothed in the Engine Control Module (ECM). 1.5 V in the display corresponds to Oxygen Sensor (O2S) 1.

(Cont.)
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







Evaluating display group 032







Evaluating display group 033







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 Test box V.A.G 1598/31
terminal 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).