Oxygen Sensor Before Catalyst, Checking

Oxygen sensor control and Heated oxygen sensors -G39- and -G108- before catalytic converter, checking

Special tools and equipment

VAG 1526 A
VAG 1594 A
VAG 1598/31
VAS 5051 with VAS 5051/1 - or
V.A.G 1551 with V.A.G 1551/3 A

NOTE:
- For specific malfunction search, it is possible to switch off the oxygen sensor control by selecting display group 99 "Basic setting" mode and to switch it on again by selecting display group 99 in "Read measured value block" mode.
- After selecting the display group 99 (whether in "Basic setting" or "Read measured value block" mode), it is possible to switch back and forth between the functions 04 "Basic setting" and 08 "Read measured value block" by pressing the keys 4 or 8 on V.A.G 1551.
- On leaving function 04 "Basic setting", the oxygen sensor control is automatically reactivated.

Test conditions
- Perform road test and do not erase Diagnostic Trouble Code (DTC) memory.
- Coolant temperature at least 85 degrees C.

Functional test
- Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. For this purpose, engine must be running at idle speed.
Connecting VAS 5051 Scan Tool
[1][2]Scan Tool Connecting and Initial Checks

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

NOTE: During basic setting, the EVAP canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.

Indicated on display:

Basic setting
Enter display group number XXX

- Press keys 0, 3 and 0 for "display group number 30" and confirm entry with Q key.

Indicated on display: (1...4 display zones)

System in basic setting 30 ->
1 2 3 4

- Check oxygen sensor status (display zones 1 to 4).

NOTE: The "oxygen sensor status" indicates the condition of the oxygen sensor control and the oxygen sensors.

Display Group 30:

Meaning of 3 digit readout of display group 30

Meaning of 3 digit readout of display group 30:

Checking oxygen sensor learned values and oxygen sensor control

- Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control module 1 with "Address word" 01. For this purpose, engine must be running at idle speed.
Connecting VAS 5051 Scan Tool
[1][2]Scan Tool Connecting and Initial Checks

Indicated on display

Rapid data transfer HELP
Select function XX

- Press keys 0 and 4 for function "Introduction of basic setting" and confirm entry with Q key.

NOTE: During basic setting, the Evaporative Emission (EVAP) canister purge regulator valve -N80- is closed and the air conditioner compressor is switched off.

Indicated on display

Basic setting
Enter display group number XXX

- Press keys 0, 3 and 3 for "display group number 33" and confirm entry with Q key.

Indicated on display: (1...4 display zones)

System in basic setting 33 ->
1 2 3 4

- Check oxygen sensor control (display zones 1 to 4):

Display Group 33:

- Press Ckey.
- Press keys 0, 3 and 2 for "display group number 32" and confirm entry with Q key.

Indicated on display: (1...4 display zones)

System in basic setting 32 ->
1 2 3 4

- Check oxygen sensor control (display zones 1 to 4):

Display Group 32:

If specification is not attained in display zone 1 or display zone 3, or if the value does not fluctuate by at least 2%:

- Check oxygen sensor heating. Oxygen Sensor Heating, Checking
- Check oxygen sensor signal wiring and actuation Oxygen Sensor Signal Wiring and Actuation, Checking
- Check intake system for leaks and correct unmetered air
- Checking fuel pressure regulator. Fuel Pressure Regulator and Holding Pressure, Checking
- Fuel return line kinked or blocked.
- Press ->key.
- Press keys 0 and 6 for the "End output" function and press Q key to confirm entry.
- Switch ignition off.

Evaluation of display group 32

Display Group 32:

Evaluation of display group 33