Operation CHARM: Car repair manuals for everyone.
Hosted by mcallihan.com

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).