Heater Check

Heated Oxygen Sensor (HO2S) -G39- Before Three Way Catalytic Converter (TWC), Checking

NOTE: Only gold plated terminals may be used to repair the contacts in the oxygen sensor harness connectors.

Special tools and equipment
- VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable
- VAG 1598/31 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram

Test requirements







- Fuse 43 OK
- Battery (B+) voltage at least 11.5 V
- Fuel pump relay OK

Test sequence
- Connect VAG1551 (VAG1552) Scan Tool (ST).
- Switch ignition on and press buttons -0- and -1- to insert "Engine Electronics" address word 01. When doing this engine must be running at idle.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08.

Indicated on display


Read Measuring Value Block
Input display group number XXX


- Press buttons -0-, -4- and -1- to input display group number 41 (041) and press -Q- button to confirm input.

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


Read Measuring Value Block 41 ->
1 2 3 4


- Check specified values for oxygen sensor heater in display field 2.

Display Group 041:

If the specified value is obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.

Continuation

If the specified values are not obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.







- Remove protective cover (arrows) and disconnect 6-pin harness connector (black) -1- to Heated Oxygen Sensor (HO2S) -G39- before Three Way Catalytic Converter (TWC).

Checking voltage supply







- Connect multimeter using aux. cables from VW1594 to measure voltage at terminals -3- and -4- (harness connector to Engine Control Module (ECM)).
- Start engine and run at idle.
- Measure voltage supply and observe display group 41, display field 2.

Display: Htg.bC.ON
- Specified value: 11.0-14.5 V

Display: Htg. bC.ON/Htg.bC.OFF (alternating)
- Specified value: Between 0.0-12.0 V fluctuating

- Switch ignition off.

If no voltage is present:
- Remove wiper arms and plenum chamber cover.







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







- Check wiring between test box and 6- pin harness connector for open circuit according to wiring diagram.
Terminal -4- + socket 5:
Wire resistance: max. 1.5 ohms

If the specified value is obtained:
- Check wire between 6-pin harness connector terminal -3- and Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms