Oxygen Sensor and Oxygen Sensor Control Before Catalytic Converter, Checking

Oxygen Sensor And Oxygen Sensor Control Before Catalytic Converter, Checking







Special tools and equipment
- VAG1526A or Fluke 83 Multimeter
- VAG1594A Connector test kit
- VAG1598/31 Test box
- VAS5051 Vehicle diagnosis, testing and information system with VAS5051/1 Adapter

Requirement
- Exhaust system free of leaks
- Coolant Temperature at least 80 degrees C.

Work sequence
- Connect VAS5051 tester, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions and select vehicle system "01 - Engine electronics". Engine must run at idle.







Display on VAS5051:
- In selection -1-, click on diagnostic function "04 - Basic Setting".







Display on VAS5051:
1 - Enter display group. Max. input value = 255

- Select function "030" in button field -2- for "display group number 030" and press Q button to confirm input.







Display on VAS5051:
- Check specified value in display field 1.

NOTE:
- Increase engine speed to obtain specified values faster.
- "Oxygen sensor status" indicates status of oxygen sensor control and oxygen sensors.

















Display on VAS5051:
Do not continue test until indication in display field 1 has reached "111" at least once.

Checking oxygen sensor adaptation values and control

- Press s button 2 times to change into display group 032.
- Check oxygen sensor adaptation values in display fields 1 and 2.












Display on VAS5051:
- Press s button to change into display group 033.
- Check oxygen sensor control in display fields 1 and 2.







Continuation

If specified value in display field 1 is not obtained or if value does not fluctuate at least 2 %:
- Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 1 is not obtained even after road test or if value does not fluctuate at least 2 %:
- Check primary voltage.
- Check oxygen sensor heater before catalytic converter.
- Check oxygen sensor before catalytic converter for aging.

Display group 032










Evaluation display group 033







Checking primary voltage
- Disconnect 6-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.







- Connect multimeter between terminal 1 and 5 for voltage measurement
- Switch ignition on.
- Specified value: 0.400 ... 0.500 V
- Switch ignition off.

If specified value is not obtained:
- Check oxygen sensor wiring.

If specified value is obtained:
- Replace Heated Oxygen Sensor (HO2S) -G39-.

Checking oxygen sensor wires
- Disconnect 6-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM) but do not connect ECM. Scan Tool Testing and Procedures







- Check following wiring connections for open circuit.

Harness connector VAG1598/31 test box
Terminal Socket
1 70
2 71
5 51
6 52

- Repair open circuit in wiring if necessary.
- Check wires to each other for short circuit.

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