With Manufacturer's Scan Tool
Heated Oxygen Sensor (O2S) and oxygen sensor control after Three Way Catalytic Converter (TWC), checking
Special tools and equipment
- V.A.G 1551 Scan Tool (or VAG 1552 mobile scan tool) with VAG 1551/3 cable
- VAG 1598/31 test box
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1594 connector test kit
- Wiring diagram
Test requirements
- Fuse no.34 must be OK.
- Exhaust system must be properly sealed between catalytic converter and cylinder head.
- Coolant temperature must be at least 85°C, See display group 04, display field 3
Function test
- Connect V.A.G 1551 scan tool (VAG 1552). Start engine and select Engine Control Module (ECM) using address word 01. Refer to Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting V.A.G 1551 Scan Tool [1][2][3]Connecting VAG 1551 Scan Tool
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- Press 0, 3 and 0 for the function "display group number 30", and then press Q to exit from input mode.
Indicated on display (1 - 4 = display fields)
Read Measuring Value Block 30 ->
1 2 3 4
- Check status of oxygen sensor control after catalytic converter (display fields 2 and 4).
Specification: 1 1 1
NOTE: The bits in display fields 2 and 4 are set to 1 only after the catalytic converter temperature has risen to over 250°C (See display groups 34 and 35, display field 2).
Meaning of 3-place number block in display fields 2 and 4:
If oxygen sensor heater is not active, that is if it stays at 0:
- Test oxygen sensor heater after catalytic converter. With Manufacturer's Scan Tool
If Heated Oxygen Sensor (O2S) or oxygen sensor control after Three Way Catalytic Converter (TWC) is not active:
Checking Primary Voltage
- Keep engine running.
- Unplug 4-pin harness connector going to corresponding Heated Oxygen Sensor (HO2S):
Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1 4-pin harness connector (green) (arrow).
- Use auxiliary wires from VAG 1594 to connect multimeter with terminals 3 + 4 (connector going to Motronic control module) to make voltage measurement, and measure primary voltage.
Specification: 0.40-0.50 V
- Unplug 4-pin harness connector going to corresponding Heated Oxygen Sensor (HO2S):
Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2 4-pin harness connector (brown) (arrow).
- Use auxiliary wires from VAG 1594 to connect multimeter with terminals 3 + 4 (connector going to Motronic control module) to make voltage measurement, and measure primary voltage.
Specification: 0.40-0.50 V
If specified value is not obtained:
- Switch ignition off.
- Test oxygen sensor wires.
Checking Wires of Heated Oxygen Sensor (HO2S) 2 Bank 1
- Connect VAG 1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.
- Check for breaks in wires between test box and 4-way connector going to Motronic control module (see wiring diagram).
Terminal 3 + socket 68
Terminal 4 + socket 69
Wire resistance: max. 1.5 Ohms
Checking Wires of Heated Oxygen Sensor (HO2S) 2 Bank 2
- Check for breaks in wires between test box and 4-way connector going to Motronic control module (see wiring diagram).
Terminal 3 + socket 10
Terminal 4 + socket 11
Wire resistance: max. 1.5 Ohms
If the specified value is met:
- Replace appropriate Heated Oxygen Sensor (HO2S) after catalytic converter.
NOTE: When servicing terminals 3 and 4 in harness connectors of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).
- Check DTC memory, repair any malfunctions and then erase DTC memory. Refer to Displaying and Reading Trouble Codes/With Manufacturer Scan Tool/DTC Memory Checking and Erasing DTC Memory Checking and Erasing
- Read readiness code. If DTC memory was erased or Engine Control Module (ECM) was disconnected from continuous B+ supply, readiness code must be re-generated. Monitors, Trips, Drive Cycles and Readiness Codes