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.G1551 scan tool or V.A.G1552 mobile scan tool with V.A.G1551/3B cable
- V.A.G1598/31 test box
- V.A.G1526 or Fluke 83 multimeter
- V.A.G1594 adapter set
- 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 degrees C, see display group 04, display zone 3.
Functional check
- Connect V.A.G1551 scan tool (V.A.G1552). Start engine and select "Address word" 01 of engine control module. Engine must be running at idling speed. (Connecting scan tool and selecting engine control module. [1][2][3]Connecting VAG 1551 Scan Tool)
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.
Indicated on display:
Read measured value block HELP
Input display group number XXX
- Press keys 0, 3 and 0 for the "Display group number 30" and confirm entry with Q key.
Indicated on display: (1 to 4 = Display zones)
Read measured value block 30
1 2 3 4
- 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:
If the specification is not obtained:
- 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 4 = Display zones)
Read measured value block 36
1 2 3 4
- 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-S2 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. DTC Memory, Checking and Erasing (Functions 02 and 05)
- Test drive vehicle to remove possible residue on oxygen sensor and repeat check.
Observe the valid safety precautions when performing 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. DTC Memory, Checking and Erasing (Functions 02 and 05)
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness 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 auxiliary cables from V.A.G1594 to measure voltage at contacts 3 + 4 (connector to Motronic control module).
- Start engine and measure basic voltage.
Specification: 0.40 to 0.50 V
- Switch ignition off.
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 malfunctions and then Erase DTC Memory. DTC Memory, Checking and Erasing (Functions 02 and 05)
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes
Checking oxygen sensor wiring, oxygen sensor 2
- Connect V.A.G1598/31 test box to control module wiring harness. 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
- Check wiring at 4-pin connector for short to one another.
Contact 4 and socket 68
Specification: Infinite Ohms
If no wiring fault is detected:
- Replace engine control module.