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.