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Oxygen Sensor Control/HO2S -G39- and -G108-, Checking



Oxygen Sensor Control / Heated Oxygen Sensor (HO2S) -G39- And Heated Oxygen Sensor (HO2S) 2 -G108-, Checking

Special tools and equipment required







- V.A.G 1526 A
- V.A.G 1594 A
- V.A.G 1598/31
- VAS 5051 with VAS 5051/1

NOTE: For defined fault finding, the oxygen sensor control can be deactivated under "Basic setting" and activated again under "Reading measured value block" on selecting display group 99.

Requirements
- No leaks in exhaust system
- Coolant temperature at least 80 degrees C see, Display group 004, display zone 3

Work sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Engine must be idling. Connecting VAS 5051 Scan Tool

Indicated on VAS 5051:







- From list -1- select diagnostic function "04 - Basic setting".

Indicated on VAS 5051:







1 Enter display group
- Use keypad -2- to enter "030" for "Display group number 030" and confirm by touching Q key.

Indicated on VAS 5051:







- Check display in zones -1- and -3-.

NOTE:
- Specifications are obtained faster by increasing engine speed.
- "Oxygen sensor status" indicates status of oxygen sensor control and oxygen sensors.


Display Group 30:






NOTE: Only the last three positions on the right in the five-position display (in zones 1 and 3) or the four-position display (in zones 2 and 4) are relevant.

Explanatory notes on 3-position display in display group 30

NOTE: Only the last three positions on the right in the five-position display (in zones 1 and 3) or the four-position display (in zones 2 and 4) are relevant.







NOTE: First zone of 3-position display (heating) fluctuates between 0 and 1.

Indicated on VAS 5051:







- Do not continue with test until display in zones -1- and -3- has reached "00111" at least once.
- Touch <- key.

Checking oxygen sensor learned values and control

Indicated on VAS 5051:







1 Enter display group
- Use keypad -2- to enter "033" for "Display group number 033" and confirm by touching Q key.
- Check display in zones -1- to -4-.
- Check oxygen sensor control (display zones 1 to 4).







- Touch <- key.

Indicated on VAS 5051:







1 Enter display group
- Use keypad -2- to enter "032" for "Display group number 032" and confirm by touching Q key.

Indicated on VAS 5051:







- Activate basic setting by touching key -A-.
- Check display in zones -1- to -4-.


Display Group 32 : Oxygen Sensor Learned Values At Idle:






- Terminate function "04 - Basic setting" by touching <- key.

If reading in display zone 1 or 3 (display group 33) does not match specification or if value does not fluctuate by at least 2 %:

- Perform test drive to remove any residue from oxygen sensors and repeat test.

=> Continued
If reading in display zone 1 or 3 still does not match specification following test drive or if value does not fluctuate by at least 2 %:
- Check oxygen sensor heating. Oxygen Sensor Heating, Checking
- Check oxygen sensor signal wire and actuation. Oxygen Sensor Signal Wire and Actuation, Checking
- Check intake system for leaks and eliminate unmetered air. Testing and Inspection
- Check fuel pressure regulator. Testing and Inspection
- Check if fuel return pipe is kinked or clogged.


Evaluation Of Display Group 32:




Evaluation Of Display Group 32:




Evaluation Of Display Group 33: