Heater Check

Heated Oxygen Sensor (HO2S) After Three Way Catalytic Converter (TWC), Checking

Special tools and equipment
- VAG1551 Scan Tool (ST) Or VAG1552 mobile scan tool with VAG1551/3 adapter cable
- VAG1598/31 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 and press -0- button to confirm input.

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 4.

Display Group 041:

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







- Remove protective cover (arrows) and disconnect 4-pin harness connector -1- to Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC) -G130-.

Checking voltage supply







- Connect multimeter using aux. cables from VW1594 to measure voltage at terminals -1- and -2- (harness connector to Engine Control Module (ECM)).
- Start engine and run at idle
- Measure voltage supply and observe display group 41, display field 4.
Display: Htg.aC.ON
- Specified value: 11.0-14.5 V
Display: Htg.aC.ON/Htg.aC.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 for open circuit between test box and 4-pin connector according to wiring diagram.
Terminal 2 + socket 63

Wire resistance: max. 1.5 ohms

If the specified value is obtained:
- Check wire between 4-pin harness connector terminal -1- and Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms