Heater Check

Heater Check

Special tools and equipment
- VAG1551 scan tool or VAG1552 mobile scan tool with VAG1551/3B cable
- VAG1598/31 test box
- VAG1526 hand multimeter or VAG1715 multimeter
- VAG1594 adapter set
- Wiring diagram

Check conditions







- All fuses must be OK.
- The battery voltage must be at least 11.5 V.
- Fuel pump relay must be OK

Test sequence
- Connect VAG1551 scan tool (VAG1552). Start engine and select "Address word" 01 of engine control module. When doing this the engine must be running at idling speed. Connecting scan tool and selecting engine control module). Refer to "VAG1551 Scan Tool Tools and Equipment

Indicated on display:


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Indicated on display:


Read measured value block HELP
Input display group number XXX


- Press keys 0, 4 and 1 for "Display group number 41" and confirm entry with Q key.

Indicated on display:(1 to 4 = Display zones)


Read measured value block 41 ->
1 2 3 4


- Run engine for 2 minutes at idling speed.
- Check oxygen sensor heater status in display zone 4:
Display: Htg.aC.ON, Htg.aC.OFF (alternating)

If the display does not indicate as described:
- Press -> key.
- Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
- Switch ignition off.







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







- Set multimeter to check resistance and connect it to contacts 1 + 2 of oxygen sensor connector. Check oxygen sensor heating for continuity.

If it is determined that oxygen sensor heating has an open circuit:
- Replace the Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC) (G130).
- Check DTC Memory, if necessary, repair any malfunctions and then Erase DTC Memory. Refer to "Displaying and Reading Trouble Codes/With Manufacture Scan Tool/Check DTC Memory (Function 02)" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again: Refer to "Monitors, Trips and/or Drive Cycle/ Reading Readiness Code" Testing and Inspection
Engine code AWW, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection
Engine code AWP, Refer to "Monitors, Trips and/or Drive Cycle/Generating Readiness Code" Testing and Inspection

If oxygen sensor heating has continuity:







- Set multimeter to measure voltage and connect to contact 1 (connector to engine control module) and Ground (GND).
- Start engine and run at idling speed.
- Check voltage supply:
Specification: 11.0 to 14.5 V

If no voltage is present:
- Check wiring from contact 1 to fuel pump relay (J17) according to wiring diagram.

If the specification is obtained:







- Connect multimeter using aux. cables from VAG1594 to measure voltage at contacts 1+2 (connector to engine control module).
- Measure voltage supply:
When display group 41, display zone 4 displays
Display, Htg.aC.ON:
Specification: 11.0 to 14.5 V
Display, Htg. aC.ON/Htg.aC.OFF (alternating)
Specification: Between 0.0 to 12.0 V fluctuating

If the specification is not obtained:
- Switch ignition off.







- Connect VAG1598/31 test box to control module wiring harness. The engine control module remains disconnected.







- Check wiring between test box and 4-pin connector for open circuit using wiring diagram.
Contact 2 and socket 63
Wire resistance: Max. 1.5 Ohm

If no fault in wire is detected:
- Replace engine control module.