Oxygen Sensor and Oxygen Sensor Control, Checking

Oxygen Sensor And Oxygen Sensor Control, Checking

Only vehicles with engine code BEW

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

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

Requirements







- The respective fuses of Diesel-Direct fuel injection system must be OK.
- Battery voltage 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 position -P- or -N-
- 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 => page ST-16. Diagnostic mode 1: Check measured values; PID 5, Coolant temperature. Diagnostic Mode 1: Check Measured Values
- Oxygen sensor heater for oxygen sensor must be OK, check => page 23-101.

Checking primary voltage
- Disconnect 6-pin harness connector to Heated Oxygen Sensor (HO2S) -G39- Harness connector of oxygen sensor is located at vehicle floor under a synthetic cover.







- Connect multimeter to terminals 2 + 6 of connector to control module for Diesel-Direct fuel injection system for voltage measurement.
- Switch on ignition and measure primary voltage.

Specified value: 0.400 to 0.500 Volts

- Switch ignition off.

If specified value is obtained:
- Replace Heated Oxygen Sensor (HO2S) -G39-.
- Erase DTC memory of control module for Diesel-Direct fuel injection system. Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If specified value is not obtained:
- Test oxygen sensor wires.

Checking oxygen sensor wires
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test
- Connect adapter cable (V.A.G 1598/39-2) to test box (V.A.G 1598/42).







- Check wires between test box and 6-pin connector (to control module for Diesel-Direct fuel injection system) for open circuit according to wiring diagram.

Terminal 1 + socket 32
Terminal 2 + socket 10
Terminal 5 + socket 54
Terminal 6 + socket 77

Wire resistance: max. 1.5 Ohms

- Check wires for short circuit to B+ and to Ground (GND).

Specified value: Infinite Ohms

If no malfunctions are found in wires:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-.
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes