Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/22
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Check conditions

• ● → Fuse 43 must be OK.
• ● The battery voltage must be at least 11.5 V.
• ● Fuel pump relay must be OK

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit .)

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

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

• ‒ Check Lambda probe heater resistance in display zone 3
       Specification: 6.4...47.5 ω

• ‒ Check Lambda probe heater status in display zone 4:
       Display: Htg.aC.ON, Htg.aC.OFF (alternating)

If the specifications are not attained:

• ‒ → Remove protective cover -arrows- and separate 4-pin connector (brown) to Lambda probe after catalyst (G130).

• ‒ → Check probe heating for continuity at Lambda probe connector contacts 1 and 2.

If it is determined that probe heating has an open circuit:

• ‒ Renew the Lambda probe after catalyst (G130).

If probe heating has continuity:

• ‒ → Set multimeter to measure voltage and connect to contacts 1 and 2 on connector to control unit.
• ‒ Start engine and run at idling speed.
• ‒ Measure the voltage supply:
  When display group 41, display zone 4 displays
  Display, Htg.aC.ON:
       Specification: 11.0...14.5 V
  Display, Htg. aC.ON/Htg.aC.OFF (alternating)
       Specification: Between 0.0...12.0 V fluctuating
• ‒ Switch off ignition.

If no voltage is present:

• ‒ → Connect test box V.A.G 1598/22 to control unit wiring harness.

• ‒ → Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
       Contact 2+socket 28
       Wire resistance: Max. 1.5 ω

If the specification is obtained:

• ‒ Check wiring from contact 1 to fuel pump relay (J17) according to current flow diagram.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder