With Generic Scan Tool

Check Oxygen Sensor And Oxygen Sensor Regulation Before Catalytic Converter

NOTE:
- Vehicle must be raised before connector for oxygen sensor is accessible.
- When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements







- The respective fuses of Heated Oxygen Sensor (HO2S) -G39- must be OK.
- 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.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- If vehicle is equipped with an A/C system, it 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.
- Coolant temperature must be at least 80 degrees C, Diagnostic mode 1: Check measuring values; PID 5, Coolant temperature. Diagnostic Mode 1: Check Measured Values
- Oxygen sensor heaters for oxygen sensors before catalytic converter must be OK, check. Oxygen Sensor Heater Before Three-Way Catalytic Converter (TWC), Checking

Function test
- Select the following output of oxygen sensor signals and check whether the specified values are being reached, Diagnostic mode 5: Check output of oxygen sensor signals. Diagnostic Mode 5: Check Output of Oxygen Sensor Signals

If specified values are obtained:
- End diagnosis and switch ignition off.

If specified values are not obtained:
- Test oxygen sensor wires.

Checking oxygen sensor wires







- Unscrew protective cover (arrows) and disconnect 6-pin harness connector (black) -1- to Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.
- Connect test box to control module wiring harness, connect test box for wiring test.







- Check wires between test box and 6-pin connector (to control module) for open circuit according to wiring diagram.
Terminal 1 + socket 70
Terminal 2 + socket 71
Terminal 5 + socket 51
Terminal 6 + socket 52
Wire resistance: max. 1.5 ohms

- Also check wires for short circuit to B+ and Ground (GND).
Specified value: Infinite Ohms

If no malfunctions are found in wires:
- Replace Heated Oxygen Sensor (HO2S) -G39- Bank 1 before catalytic converter, item 8
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes