Heated Oxygen Sensor (HO2S), Checking
Heated Oxygen Sensor (HO2S), checking^ Engine warm
^ Exhaust system tree of leaks between cylinder head and Three-way Catalytic Converter (TWC)
^ Heated Oxygen Sensor (H02S) voltage supply OK
^ VAG 1551 Scan Tool (ST) connected. Connecting VAG 1551 Scan Tool
- Start engine and let idle.
- Operate VAG 1551 Scan Tool (ST) according to information indicated on display:
^ Rapid data transfer operating mode
^ Address word 01 for "Engine Electronics"
- Indicated on display
[Rapid data transfer HELP ]
[Select function XX ]
- Press buttons -0- and -8- to select "Read Measuring Value Block" function.
- Press button -Q- to confirm input.
- Indicated on display
[Read measuring value block HELP ]
[Enter display group number XX ]
- Press button -0- twice to enter display group number 00, and press -Q- button to confirm input.
- Indicated on display
(1-10 = display fields)
[Read measuring value block => ]
[1 2 3 4 5 6 7 8 0 10 ]
- Observe value in display field 1 (coolant temperature).
^ Specification: max. 22 (corresponds to mm. 85°C or 185°F coolant temperature)
Note: If necessary run the engine until the coolant reaches the minimum temperature, until the displayed value is below the maximum.
- Observe value in display field 5 (Oxygen Sensor control).
^ Specification: 106 to 150, fluctuating
- Observe value displayed in display field 6 (altitude correction factor):
If the value is within the specified range:
- Press => button.
- Press buttons -0- and -6- to select "End Output" function.
- Press -Q- button to confirm input.
If the value displayed is not as specified:
- Leave engine running at idle and check Intake Air system for leaks (unmetered air) Testing and Inspection
- Check Spark Plugs, Spark Plug connectors and ignition cables.
- Check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) for leaks.
^ Valve must remain closed for approx. 5 seconds after switching ignition off.
- Check Heated Oxygen Sensor (H025) probe for plugging and replace if necessary.