With Manufacturer's Scan Tool
Oxygen Sensor And Oxygen Sensor Control Before Catalyst, Checking
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
- 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. When doing this the 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 before catalyst (display zone 1):
Specification: 1 1 1
Significance of 3 digit number block in display zone 1:
If the specification is not obtained:
- If the specification is not obtained:
If the specification is obtained:
- Check 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:
- See Evaluating display group 32. Display Groups 30 to 49, 99, 107 (Oxygen Sensor Control)
If the specification is obtained:
- Check display group 33 as follows:
V.A.G1551: Press key 3
V.A.G1552: Press key
Indicated on display: (1 to 4 = Display zones)
Read measured value block 32
1 2 3 4
- Observe oxygen sensor control in display zone 1. 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 "End data transfer" function and confirm input with Q key.
- Road test vehicle to burn oxygen sensors clean, then repeat check.
Observe the valid safety precautions when performing a road test.
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 Heated Oxygen Sensor (HO2S) -G39-.
- 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
- Connect V.A.G1598/31 test box to control module wiring harness. 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 Ohms
- Check all wires for short to one another.
Specification: Infinite Ohms
If no wiring malfunction is detected:
- Replace Heated Oxygen Sensor (HO2S) -G39-.
- 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