Oxygen Sensor and Oxygen Sensor Regulation Before Catalytic Converter, Checking

Oxygen Sensor And Oxygen Sensor Regulation Before Catalytic Converter, Checking

NOTE: Use only gold-plated terminals when servicing terminals in the harness connector.

Recommended special tools and equipment
- V.A.G1526 multimeter or V.A.G1715 multimeter
- V.A.G1594 connector test kit
- Wiring diagram

Test requirements







- Fuses on E-box in engine compartment, left side, must be OK.

NOTE: Fuses on this fuse holder are labelled "SB" in the wiring diagram.







- Fuses on fuse holder in instrument panel, left side, must be OK.

NOTE: Fuses on this fuse holder are labelled "SC" in the wiring diagram.

- Battery voltage must be at least 11.5 Volts.
- All electrical consumers such as, lights and rear window defroster must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- Exhaust system must be properly sealed between catalytic converter and cylinder head.
- Oxygen sensor heater for oxygen sensor before catalytic converter must be OK, check.

Function test
Observe safety precautions.
Observe rules for cleanliness.

- Select "Test-ID 1 ($1): Oxygen sensor before catalytic converter" and check whether specified value is reached.
- End diagnosis and switch ignition off.

If specified value is not obtained:
- Check wires to Engine Control Module (ECM) according to wiring diagram.

Checking wires to Engine Control Module (ECM)
- Connect test box to 94-pin connector of wiring harness. Test Box, Connecting For Wiring Test

Engine Control Module (ECM) is not connected.







- Disconnect black 6-pin harness connector -arrow- to Heated Oxygen Sensor (HO2S) G39-.







- Check wires between test box and 6-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.

Terminal 1 + socket 60
Terminal 2 + socket 61
Terminal 5 + socket 81
Terminal 6 + socket 82

Wire resistance: max. 3.0 Ohms

- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: Infinity Ohms

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no malfunctions are found in wires:
- Replace Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.
- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes