Heated Oxygen Sensor and Oxygen Sensor Control, Checking

Diagnostic Procedures

Heated Oxygen Sensor and Oxygen Sensor Control, Checking

• Cylinder bank 1 is located in direction of travel, right.

• Cylinder bank 2 is located in direction of travel, left.

• Use only gold-plated terminals when servicing terminals in harness connector.

Special tools, testers and auxiliary items required

• Multimeter (VAG1526) or Multimeter (VAG1715)

• Connector test kit (VAG1594)

• Wiring diagram

Test Prerequisites

• Fuses in E-box (plenum chamber, left) must be OK:

• Power Supply Relay (Terminal 30, B+) Relay 2 (J689), must be OK, check:

• 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.

• 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°C --> [ Diagnostic Mode 01 - Read Current System Data ] .

• Oxygen sensor heater for oxygen sensors must be OK, check --> [ Oxygen Sensor Heater, Checking ]Oxygen Sensor Heater, Checking.

Cylinder bank 1: Check Heated Oxygen Sensor (HO2S) (G39).

Cylinder bank 2: Check Heated Oxygen Sensor (HO2S) 2 (G108).

Heated Oxygen Sensor 2 (G39), Test Sequence

- Connect diagnostic tester.

- Start engine and let it run at idle.

- Under address word 33, select "Diagnostic mode 1: Check measured values."

- Select the measuring value "PID 36: Oxygen sensor value Bank 1 Sensor 1".

- Check specified value of oxygen sensor:

* If a voltage greater than 0.0 volts is displayed, oxygen sensor is activated.

- End diagnosis and switch ignition off.

If specified values are not obtained:

- Check Control Module Wires.

Control Module Wires, Checking

- Connect test box ((VAG1598/42)) to Engine Control Module (ECM) (J623) wiring harness using adapter cable ((VAG1598/39-2)) , connecting test box for wiring test.

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

- Check wires between test box and 6-pin connector 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. 1.5ohms

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

Specified value: infinite ohms

If no malfunctions are found in wires:

- Replace Heated Oxygen Sensor (HO2S) (G39).

- Erase DTC memory of Engine Control Module (ECM) --> [ Diagnostic Mode 04 - Erase DTC Memory ] .

- Generate readiness code --> [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

Heated Oxygen Sensor 2 (G108) Test Sequence

- Connect diagnostic tester.

- Start engine and let it run at idle.

- Under address word 33, select "Diagnostic mode 1: Check measured values."

- Select the measuring value "PID 40: Oxygen sensor value Bank 2 Sensor 1".

- Check specified value of oxygen sensor:

* If a voltage greater than 0.0 volts is displayed, oxygen sensor is activated.

- End diagnosis and switch ignition off.

If specified values are not obtained:

- Check Control Module Wires.

Control Module Wires, Checking

- Connect test box ((VAG1598/42)) to Engine Control Module 2 (J624) wiring harness using adapter cable ((VAG1598/39-2)) , connecting test box for wiring test.

- Disconnect 6-pin harness connector - A - to Heated Oxygen Sensor (HO2S) 2 (G108).

- Check wires between test box and 6-pin connector for open circuit according to wiring diagram.