With Manufacturer's Scan Tool

Oxygen Sensor Heater For Heated Oxygen Sensor (H02S) -G39-, Checking

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.

Special tools and equipment
- V.A.G1551 scan tool (or VAG1552 mobile scan tool) with VAG1551/3 cable
- VAG1598/31 test box
- Multimeter Fluke 83 or equivalent
- VAG1594 connector test kit
- Wiring diagram

Test requirements





- All fuses must be OK.
- Battery voltage must be at least 11.5 volts.
- Fuel Pump (FP) relay must be OK.
- Connect V.A.G 1551 scan tool (VAG1552). Start engine and select the Engine Control Module (ECM) using address word 01. [1][2]Reading and Clearing Diagnostic Trouble Codes

Indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.

Indicated on display:

Read measuring value block
Enter display group number XXX

- Press buttons -0-, -4- and -1- to select "Display group number 41". Press -Q- button to confirm input.

Indicated on display: (1 to 4 = display fields)

Read measuring value block 41 ->
1 2 3 4

- Let engine run at idle for 2 minutes.

- Check the status of the oxygen sensor heater in display field 2:
Display: Htng.bef.cat.ON,
Htng.bef.cat.OFF (alternating)

NOTE: Depending on the operating condition of the engine, oxygen sensor heating can be switched on or off, i.e. the indications in display field 2 or 4 can be either Htng.bef.cat.ON or can alternate between Htng.bef.cat.ON/Htng.bef.cat.OFF.

If indications do not resemble description:
- Press -> button.
- Press buttons -0- and -6- to select "End data transfer" function 06. Press -Q- button to confirm input.
- Switch ignition off.






- Unscrew protective cover (arrows) and disconnect 4-pin harness connector (black) -1- to Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.






- Set multimeter for resistance measurement and connect it to terminals 3 + 4 at connector for oxygen sensor. Check oxygen sensor heater for continuity.
Specification: 2.5 to 10 Ohms (at room temperature)

If a short circuit is found in the oxygen sensor heater:
- Replace Heated Oxygen Sensor (HO2S) -G39-.
- Check DTC memory, repair any malfunctions and then erase DTC memory.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes

If oxygen sensor heater has continuity:






- Set the multimeter to voltage measurement and connect it to terminal 3 (connector for Engine Control Module -ECM-) + Ground (GND).
- Start engine, and let run at idle.
- Measure voltage supply:
Specification: 11.0 to 14.5 V

If specified value is not obtained:
- Check wire connection from terminal 3 to Fuel Pump (FP) relay -J17- according to wiring diagram.

If specified value is obtained:






- Use adapter cables from VAG1594 to connect multimeter to terminals 3 + 4 (ECM connector) for voltage measurement.
- Check activation from Engine Control Module (ECM) and observe display group 41, display field 2.
Htng.bef.cat.ON indicated:
Specification: 11.5 to 14.5
VHtng.bef.cat.ON/Htng.bef.cat.OFF (alternating) indicated:
Specification: oscillating between 0.0 and 12.0 V

- Switch ignition off.

If specified value is not obtained:
- Remove wiper arms and wind cowl






- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.






- Check for open circuits in wire between test box and 6-pin connector according to wiring diagram:
Terminal 4 and test box socket 5
Wire resistance: max: 1.5 Ohms

- Also check wire for short circuit to B+ or Ground (GND).

If wiring is OK:
- Replace Engine Control Module (ECM).