Oxygen Sensor Heater For Oxygen Sensor Before Three Way Catalytic Converter (TWC), Checking
Oxygen Sensor Heater For Oxygen Sensors Before Catalytic Converter, Checking
NOTE: Use only gold-plated terminals when servicing terminals in the harness connector.
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
- Corresponding fuses on E-box in engine compartment, left side, of Oxygen Sensor (O2S) Heater -Z19- and Oxygen Sensor (O2S) 2 Heater -Z28- for Heated Oxygen Sensor (HO2S) -G39- and Heated Oxygen Sensor (HO2S) 2 -G108- must be OK.
NOTE: Fuses on this fuse holder are labelled "SB" in the wiring diagram.
- Battery voltage must be at least 11.5 Volts.
- All electrical consumers such as, for example, lights and rear window defroster must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- For vehicles with automatic transmission, selector lever must be in -P-.
- Ground (GND) connections between engine and chassis must be OK.
Function test
Observe safety precautions.
Observe rules for cleanliness.
- Select the "Monitor-ID 65 and 69 ($41 and $45): Oxygen sensor heater for oxygen sensor before catalytic converter" and check whether the specified values are reached, Diagnostic Mode 06 - Read Test Results For Specific Diagnostic Functions
- End diagnosis and switch ignition off.
If specified values are not obtained:
- Check voltage supply.
Checking voltage supply
- Disconnect the corresponding 6-pin harness connector to the oxygen sensor to be tested:
1 - 6-pin harness connector, black:
For Heated Oxygen Sensor (HO2S) -G39-
3 - 6-pin harness connector, brown
For Heated Oxygen Sensor (HO2S) 2 -G108-
- Connect multimeter to terminals 3 and 4 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.
- Replace the corresponding Oxygen Sensor (O2S):
- Heated Oxygen Sensor (HO2S) -G39-,
- Heated Oxygen Sensor (HO2S) 2 -G108-,
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If specified value is not obtained:
- Connect multimeter to terminal 4 of connector to Engine Control Module (ECM) and Ground (GND) for voltage measurement.
Specified value: at least 11.5 V
- Switch ignition off.
If specified value is not obtained:
- Check voltage supply at 6-pin connector terminal 4 to Motronic Engine Control Module (ECM) Power Supply Relay 2 -J670- according to wiring diagram.
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If specified value is obtained:
- Check wire to Engine Control Module (ECM) according to wiring diagram.
Checking wire to Engine Control Module (ECM)
- Connect test box to 94-pin connector of wiring harness, connecting test box for wiring test.
Engine Control Module (ECM) is not connected.
- Check wire between test box and 6-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Wire resistance: max. 3.0 ohms
- Also check the wire for short circuit to B+ and to Ground (GND).
Specified value: infinity 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. Monitors, Trips, Drive Cycles and Readiness Codes
If no malfunctions are found in wire:
- Replace Engine Control Module (ECM) -J623-.