With Manufacturer's Scan Tool
Oxygen Sensor and Oxygen Sensor Control After Catalyst, Checking
NOTE:
- Raise vehicle to reach Oxygen sensor connector.
- Only gold contacts may be used for servicing contacts 3 and 4 in connector for Oxygen sensor.
Special tools and equipment
- V.A.G 1551 scan tool or or 1552 scan tool with cable VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram
Check conditions
- All fuses must be OK.
- The battery voltage must be at least 11.5 V.
- Exhaust system between catalyst and cylinder head must be free of leaks
- Coolant temperature must be at least 80°C, See display group 04, display zone 3.
Functional check
- Connect V.A.G 1551 scan tool ((VAG1552). Start engine and select "Address word" 01 of engine control module. When doing this the engine must be running at idling speed. [1][2]Reading and Clearing Diagnostic Trouble Codes
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for the function "Read measuring value block" and confirm entry with Q key.
Indicated on display:
Read measuring value block
Input display group number XXX
- Press keys 0, 3 and 0 for the "Display group number 30" and confirm entry with Q key.
If the specification is not obtained:
Indicated on display: (1 to 2 = Display zones)
Read measuring value block 30 ->
1 2
- Check Oxygen sensor control status after catalyst (display zone 2):
Specification: 1 1 0
NOTE:
- The first position of the 3 digit number block fluctuates between 0 and 1 (Oxygen sensor heating on and off).
- The third position of the 3 digit number block will be set to 1 only at increased exhaust temperature and part load.
Significance of 3 digit number block in display zone 1:
- Check Oxygen sensor heating after catalyst
If the specification is obtained:
- Press C key.
- Press keys 0, 3 and 6 for "Display group number 36" and confirm entry with Q key.
Indicated on display: (1 to 2 = Display zones)
Read measuring value block 36 ->
1 2
- Check Oxygen sensor voltage after catalyst in display zone 1:
Specification: 0.100 to 0.900 V (can fluctuate slightly)
If the display in display zone 1 remains constant:
- Continue check according to following table.
Possible causes of malfunction if sensor control frequency is too slow:
- Slots or holes in sensor body are blocked
- Sensor vent hole in area of connecting wire is blocked
- Sensor has been overheated (glazed)
- Sensor has been damaged by leaded fuel
- Check diagnosis result in display zone 2:
Specification: B1-P2 OK
NOTE: It can take a few minutes until display jumps from "Test ON" to "B1-P2 OK".
If "B1-P2 nOK is displayed:
- Press -> key.
- Check DTC memory.
Reading Diagnostic Trouble Codes
- Test drive vehicle to remove possible residue on Oxygen sensor and repeat check.
Observe the valid safety precautions when carrying out a road test.
If the specifications are again not attained:
- Replace Oxygen sensor (O2S) behind three way catalytic converter (TWC) -G130-.
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes
Checking basic voltage
- Remove protective cover -arrows- and separate 4-pin connector (brown) to Oxygen sensor (O2S) behind three way catalytic converter (TWC) -G130-.
- Connect multimeter with aux. cables from VAG 1594 to measure voltage at contacts 3+4 (connector to Motronic control module).
- Start engine and measure the basic voltage.
Specification: 0.40 to 0.50 V
- Switch off ignition.
If the specification is not obtained:
- Check Oxygen sensor wiring.
If the specification is obtained:
- Replace Oxygen sensor (O2S) behind three way catalytic converter (TWC) -G130-.
- Check DTC memory, if necessary, repair any faults and then erase DTC memory.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes
Checking Oxygen sensor wiring, Oxygen sensor 2
- Remove wiper arms and cowl panel.
- Connect test box VAG 1598/31 to control module wiring harness. The engine control module remains disconnected.
- Check wiring between test box and 4-pin connector to Motronic control module for open circuit using wiring diagram.
Contact 3 and socket 68
Contact 4 and socket 69
Wire resistance: max. 1.5 Ohms
- Additionally check wiring for short to one another, and for short to battery positive or Ground.
Specification: Infinity Ohms
If no fault is detected in the pipes:
- Replace engine control module.