O2 sensor/O2 sensor control After Three Way Catalyst, checking
Oxygen sensor and Oxygen sensor control (after Three Way Catalyst), checking
Special tools, testers, measuring instruments and auxiliary items required
- VAG 1551/1552 Scan Tool with VAG 1551/3B adaptor cable
- VAG 1598/22 Test Box
- Fluke 83 Multimeter
- VW 1594 Adaptor kit
- Wiring diagram
Checking conditions
- The Engine Control Module must be matched to the Throttle Body Control Module.
- Engine Coolant Temperature must be 85 °C minimum = Display group 04, Display zone 3.
- Exhaust system between Three Way Catalyst and cylinder head must be leak tight
Functional check
- Connect VAG 1551/1552 Scan Tool, Refer to "Scan Tool Testing", [1][2][3]Reading and Clearing Diagnostic Trouble Codes
- Start engine and let idle
- Press 0 and 1 buttons to select "Address word" 01 "Engine electronics"
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and 8 buttons to select Function 08: "Read measuring value block"
- Press Q button to enter input
Display will appear as shown
Read measuring value block HELP
Input Display group number XXX
- Press 0, 3 and 6 buttons to select "Display group 36"
- Press Q button to enter input
Display will appear as shown (1 to 4 = Display zones)
Read measuring value block 36 ->
1 2 3 4
- Observe specifications in Display zones 1 and 2 on chart.
Continuation
- Perform test drive to remove possible residue and repeat check.
If specifications in Display zones 1 and 2 are not obtained even after a test drive:
- Check Oxygen sensor heating, Oxygen Sensor Heating After Catalyst Checking
- Raise engine speed above 3000 rpm.
If value in Display zone 1 remains constant, evaluating Display group 36.
Evaluating Display group 36
Basic Voltage, check
- Disconnect 4-pin harness connector (black) to Oxygen sensor G108 -1- (after Three Way Catalyst).
- Connect Multimeter between terminals 3 + 4 (ECM connector) using jumper wires from VW 1594 adaptor kit
- Start engine and measure basic Voltage.
- Specification: 0.40 to 0.50 Volts
- Switch OFF ignition.
If specification not obtained
- Check the Oxygen sensor wiring.
If specification obtained
- Replace Oxygen sensor G108 (after Three Way Catalyst).
Checking Oxygen sensor wiring
- Connect VAG 1598/22 Test Box to Engine Control Module harness connector
- Disconnect 4-pin harness connector (black) to Oxygen sensor G108 (after Three Way Catalyst) -1-.
- Check wiring for open circuit between Test Box and 4-pin harness connector (to Control Module) using Wiring diagram.
Terminal 3 + socket 51
Terminal 4 + socket 52
Wire resistance: Max. 1.5 Ohms
- Check for short circuit between connector terminals 3 + 4 and 1 + 2 using Wiring diagram.
- Specification: Infinity Ohms
If wiring OK
- Replace Engine Control Module.
NOTE: If DTC memory has been erased or the Engine Control Module was disconnected from its Voltage supply, the Readiness Code must be created again , Monitors, Trips, Drive Cycles and Readiness Codes