Oxygen Sensor: Testing and Inspection
Heated Oxygen Sensor (H02S) systemNOTE:
For functional testing of the oxygen sensor also see On-Board Diagnostics "Read Measuring Value Block" function 08, display groups 007 and/or 008. Testing and Inspection
CAUTION!
DO NOT USE SILICONE SPRAYS, SEALERS, CLEANERS, ETC. near the intake area. Traces of silicone components drawn into the engine are not burned during combustion and can damage the oxygen sensor,
DO NOT use contact sprays or similar materials in the area of the oxygen sensor connection, since these lead to corrosion damage in the oxygen sensor,
Checking Oxygen Sensor heating
Connector / Component Locations:
- Disconnect heated oxygen sensor harness connector on right or left cylinder bank.
1A - Right bank
4B - Left bank
2-Pin Connector:
- Connect multimeter (Fluke 83 or equivalent) between connector terminals 1, Ground (GND), and 2, positive (8+).
- Start engine and let idle.
^ Specified value: approx. 12-14 volts
If specified values are not obtained:
- Check HO2S circuit breaker -S73- (brown holder in electronics box, passenger side footwell).
- Check continuity in wiring from connector terminal 2 to circuit breaker using wiring diagram.
^ Specified reading: maximum 0.5 ohms
- Check continuity in wiring from connector terminal 1 to GND.
^ Specified reading: maximum 0.5 ohms
- Check fuel pump relay.
If the specified reading is obtained:
- Connect additional test harness VAG 1315 A/1 into 2-pin HO2S connector.
This series connection allows actual current flow measurement
- Switch multimeter to 10 amp (DC) measuring range and connect (connect test harness to 10 amp connector).
- Run engine.
^ Specified reading: 0.5-3.0 amps (Current decreases as sensor temperature increases).
If specified reading is not obtained:
- Replace oxygen sensor.
Checking Oxygen Sensor control
- Disconnect harness connector for oxygen sensor signal wire.
1C - Right bank
4A - Left bank
- Connect multimeter between oxygen sensor signal wire and GND.
^ Specified value: infinite ohms (no continuity)
If specified values are not obtained:
- Replace HO2S.
If specified value is obtained:
- Switch multimeter to 2.0 volt measuring range and connect between signal wire connector of wiring harness to ECM and GND.
- Switch ignition on.
^ Specified value: 400 +/- 50 mV
If specified values are not obtained, check wiring to ECM:
- Switch ignition OFF.
- Connect VAG 1598 test box on ECM wiring harness using VAG 1598/11 adapter harness. Connecting VAG 1598/31 Test Box
^ Adapter harness for ECM is not connected.
- Check for continuity between H02S -G39- signal wire and test box socket 50.
^ Specified value: max. 1 (ohm)
- Check for continuity between H02S 2 -G108- signal wire and test box socket 48.
^ Specified value: max. 1 (ohm)
If specified values are not obtained:
- Repair open or short circuit in wiring connection between connector in engine compartment and terminal 50 and/or 48 of ECM connector A according to wiring diagrams.
If there is no malfunction in wiring connection:
- Replace ECM.