Oxygen Sensor and Oxygen Sensor Regulation Before Catalytic Converter, Checking

Oxygen Sensors 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.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 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, for example, lights and rear window defroster must be switched off.
- For vehicles with automatic transmission, selector lever must be in -P-.
- Ground (GND) connections between engine and chassis must be OK.
- Exhaust system must be properly sealed.
- Oxygen sensor heaters for oxygen sensors before catalytic converter must be OK, check.

Function test
Observe safety precautions.
Observe rules for cleanliness.

- Select the "Monitor-ID 1 and 5 ($1 and $5): 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 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, connecting test box for wiring test. Test Box, Connecting For Wiring Test

Engine Control Module (ECM) is not connected.







- 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-







- Check wires 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 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 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 wires:
- 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