Oxygen Sensor Heater For Oxygen Sensors Behind Three Way Catalytic Converter (TWC), Checking
Oxygen Sensor Heater For Oxygen Sensors Behind Three Way Catalytic Converter (TWC), Checking
NOTE: When servicing terminals 3 and 4 in harness connector of oxygen sensors, use only gold-plated terminals.
Recommended special tools and equipment
- V.A.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 connector test kit
- Wiring diagram
Test requirements
- Fuses in E-box (plenum chamber, left) must be OK
- Motronic Engine Control Module (ECM) Power Supply Relay 2 -J670- -position A1- must be OK, check:
- Battery voltage must be at least 11.5 volts.
- All electrical consumers such as, lights and rear window defroster must be switched off.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in -P-.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
Test sequence
- Disconnect 4-pin harness connector to the respective oxygen sensor:
- Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-, bank 1, 4-pin harness connector 2-,
- Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131-, bank 2, 4-pin harness connector -3-.
Checking voltage supply and wiring to control module
- Connect multimeter to terminals 1 +2 of connector to Engine Control Module (ECM) for voltage measurement.
- Start engine, and let run at idle.
Specified value: at least 8.0 V
If specified value is obtained:
- Switch ignition off.
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Readiness Code
If specified value is not obtained:
- Connect multimeter to terminal 1 of connector to Engine Control Module (ECM) + Ground (GND) for voltage measurement.
Specified value: at least 11.0 V
- Switch ignition off.
If specified value is not obtained:
- Check wire between 4-pin connector terminal 1 and Motronic Engine Control Module (ECM) Power Supply Relay 2 -J670- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Readiness Code
If specified value is obtained:
- Check Ground (GND) activation of the respective oxygen sensor heater.
Checking Ground (GND) activation of oxygen sensor heating
- Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms
- Also check wires for short circuit to B+ or Ground (GND).
Specified value: infinity ohm
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Readiness Code
If no malfunctions are found in wires:
- Replace Motronic Engine Control Module (ECM) -J220-.