With Manufacturer's Scan Tool
Oxygen Sensor And Oxygen Sensor Control Before Three Way Catalytic Converter (TWC), Checking
NOTE:
- Raise vehicle to reach oxygen sensor connector.
- The Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) has constant regulation and can be distinguished by a 6-pin connector from the Oxygen Sensor (O2S) behind the Three Way Catalytic Converter (TWC).
- Only gold terminals may be used for servicing the terminals in the connector for the oxygen sensor.
Special tools, test equipment and auxiliary items
- VAG 1551 scan tool or VAG 1552 mobile scan tool with VAG 1551/3B cable
- VAG 1598/31 test box
- VAG 1526 hand multimeter or VAG 1715 multimeter
- VAG 1594 adapter set
- Electrical Wiring Diagram
Test conditions
- All fuses must be OK
- Battery voltage must be at least 11.5 V
- Exhaust system between Three Way Catalytic Converter (TWC) and cylinder head must be free of leaks
- Engine Coolant Temperature (ECT) must be at least 80°C.
Functional check
- Connect VAG 1551 scan tool ((VAG 1552). Start engine and select "Address word" 01 of Motronic Engine Control Module (ECM) -J220-. Engine must be running at idle speed. Connecting scan tool and selecting Motronic Engine Control Module (ECM) -J220-.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- for function "Read measuring value block" and confirm entry with -Q- button.
Indicated on display
Read measuring value block
Input display group number XXX
- Press buttons -0-, -3- and -0- for "Display group number 30" and confirm entry with -Q- button.
Indicated on display (1 to 2 = Display zones)
Read measuring value block 30 ->
1 2
- Check status of the oxygen sensor control before Three Way Catalytic Converter (TWC) (display zone 1):
Specification: 1 1 1
Significance of 3 digit number block in display zone 1
If the specification is obtained:
- Change to display group 32 as follows:
- Press -C- button.
- Press buttons -0-, -3- and -2- for "Display group number 32" and confirm entry with -Q- button.
Indicated on display (1 to 2 = Display zones)
Read measuring value block 32 ->
1 2
- Check oxygen sensor control learned values at idling speed (additive) in display zone 1.
Specification: -3.0...3.0%
- Check oxygen sensor control learned values at part load (multiplicative) in display zone 2.
Specification: -10.0...10.0%
If the specification is obtained:
- Change to display group 33 as follows:
VAG 1551: Press button -3-
VAG 1552: Press button uparrow
Indicated on display (1 to 2 = Display zones)
Read measuring value block 33 ->
1 2
- Observe oxygen sensor control in display zone 1. Display must fluctuate at least 2 % in the range -10.0 to 10.0%
If the specification is obtained:
- Press -> button.
- Press buttons -0- and -6- for function "End output" and confirm entry with -Q- button.
- Switch off ignition.
Continuation
If the oxygen sensor control in display zone 1 does not fluctuate as stated:
- Press -> button.
- Press buttons -0- and -6- for function "End output" and confirm entry with -Q- button.
- 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 the specifications in display zone 1 are not obtained even after a test drive, or the value does not fluctuate by at least 2%:
- Check oxygen sensor before Three Way Catalytic Converter (TWC) for aging.
Evaluating display zone 33, display zones 1 - oxygen sensor control learned values before Three Way Catalytic Converter (TWC)
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
Checking Oxygen Sensor wiring for oxygen sensor 1
- Remove inner plenum chamber cover, left.
- Connect VAG 1598/31 test box to control module wiring harness. Motronic Engine Control Module (ECM) -J220- is not connected by this action.
- Remove protective cover -arrows- and separate 6-pin connector (black) -1- to Heated Oxygen Sensor (HO2S) before Three Way Catalytic Converter (TWC) -G39-.
- Check wiring for open circuit between test box and 6-pin connector (to control module) according to Electrical Wiring Diagram.
- terminal 1 + socket 70
- terminal 2 + socket 71
- terminal 5 + socket 51
- terminal 6 + socket 52
Wire resistance: Max. 1.5 Ohms
- Additionally check wires all for short to one another.
Specification: Infinity Ohms
If no wiring malfunction is found:
- Replace Heated Oxygen Sensor (HO2S) before Three Way Catalytic Converter (TWC) -G39-.
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory.
- Read readiness code. If DTC memory has been erased or Motronic Engine Control Module (ECM) -J220- was disconnected from battery positive, readiness code must be generated again.