Sensor and Sensor Control Check
NOTE:
- Raise vehicle to reach oxygen sensor connector.
- The oxygen sensor (before catalyst) has constant regulation and can be distinguished by a 6-pin connector from the Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC).
- Only gold contacts may be used for servicing the contacts in the connector for the oxygen sensor.
Special tools and equipment
- VAG1551 scan tool or VAG1552 mobile scan tool with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 hand multimeter or VAG1715 multimeter
- VAG1594 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 °C, See display group 04, display zone 3.
Functional check
- Connect VAG1551 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. (Connecting scan tool and selecting engine control module). Refer to "VAG1551 Scan Tool Tools and Equipment
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for the 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 before catalyst (display zone 1):
Specification: 111
Significance of 3 digit number block in display zone 1:
If the specification is not obtained:
- Check the oxygen sensor heating before catalyst. Heater Check
If the specification is obtained:
- Change to display group 32 as follows:
- Press C key.
- Press keys 0, 3 and 2 for "Display group number 32" and confirm entry with Q key.
Indicated on display: (1 to 4 = Display zones)
Read measured value block 32 ->
1 2 3 4
- Check oxygen sensor learned values at idling speed (additive) in display zone 1.
Specification: -10.0 to 10.0 %
- Check oxygen sensor learned values at part load (multiplicative) in display zone 2.
Specification: -10.0 to 10.0 %
If the specification is not obtained:
- Evaluating display group 32, Refer to "Scan Tool Testing/VAG1551/Evaluating Display Group 30 to 49, 99, 107 (Oxygen Sensor Control)", Testing and Inspection
If the specification is obtained:
- Change to display group 33 as follows:
VAG1551: Press key 3
VAG1552: Press key (up arrow)
Indicated on display: (1 to 4 = Display zones)
Read measured value block 33 ->
1 2 3 4
- Observe oxygen sensor control in display zone 1. The display must fluctuate at least 2 % in the range -10.0 to 10.0 %
If the oxygen sensor control in display zone 1 does not fluctuate as stated:
- Press -> key.
- Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
- Carry out road test and burn oxygen sensors clean and repeat check.
Observe the valid safety precautions when carrying out a road test Technician Safety Information
If the the specifications in display zone 1 are not obtained even after a test drive, or the value does not fluctuate by at least 2 %:
- Replace the Heated Oxygen Sensor (HO2S)(G39).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory,Checking and Erasing DTC Memory. Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Checking oxygen sensor wiring
- Connect VAG1598/31 test box to control module wiring harness. The engine control module remains disconnected.
- Remove protective cover -arrows- and separate 6-pin connector (black) -1- to Heated Oxygen Sensor (HO2S) (G39).
- Check wiring for open circuit between test box and 6-pin connector (to control module) according to wiring diagram.
Contact 1+socket 70
Contact 2+socket 71
Contact 5+socket 51
Contact 6+socket 52
Wire resistance: Max. 1.5 Ohm
- Additionally check wires all for short to one another.
Specification: Infinity Ohm
If no wiring fault is detected:
- Replace the Heated Oxygen Sensor (HO2S)(G39).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory,Checking and Erasing DTC Memory. Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection