Oxygen Sensor Heaters After Catalytic Converter, Checking
Diagnostic Procedures
Oxygen Sensor Heaters After Catalytic Converter, Checking
• When servicing terminals 3 and 4 in harness connector of oxygen sensors, use only gold-plated terminals.
Special tools, testers and auxiliary items required
• Hand multimeter (V.A.G 1526) or Multimeter (V.A.G 1715)
• Test adapter kit (V.A.G 1594)
• Wiring diagram
Test conditions
• Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) -position 5- must be OK, check:
• Battery voltage (both batteries) must be at least 11.5 Volts.
• All electrical consumers such as, lights and rear window defroster must be switched off.
• For vehicles with automatic transmission, selector lever must be in " P".
• Parking brake must be engaged.
• The Ground (GND) connections between engine and body must be OK.
• Ignition switched off.
• Fuses in right instrument panel fuse holder must be OK:
Right instrument panel fuse holder
Voltage Supply and Wiring to Control Module, Checking
Test sequence
- Disconnect corresponding 6-pin harness connector to oxygen sensor to be tested: Component location
- Connect multimeter to terminals 1 + 2 of connector to Engine Control Module for voltage measurement.
- Start engine and run at idle speed. Specification: at least 7.0 V
If specification is obtained:
- Switch ignition off.
- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.
If specification is not obtained:
- Connect multimeter to terminal 1 of connector to Engine Control Module + Ground (GND) for voltage measurement. Specification: at least 11.0 V
- Switch ignition off.
If specification is not obtained:
- Check voltage supply at 4-pin connector terminal 1 to Motronic Engine Control Module (ECM) Power Supply Relay 2 (J670) according to wiring diagram:
- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.
If specification is obtained:
- Check Ground (GND) activation of the respective oxygen sensor heater.