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
• ◆ Chilling spray (commercially available)

Test sequence

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (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, 0 and 5 for "Display group number 5" and confirm entry with Q key.

Functional check of sender

• ‒ Note intake air temperature figure in display zone 4.

     1)     If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check sender wiring for transfer resistances.

Continuation of check:

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

• ‒ → Pull 4 pin connector -1- off air mass meter -2-.
• ‒ Check wiring between test box and 4 pin connector for open circuit using current flow diagram.
       Contact 2+ socket 12
       Contact 4+ socket 9
       Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ → Test resistance between contacts 2 and 4 of sender.

→ Scale A shows resistance values for temperature range 0...50 °C and scale B the values for temperature range 50...100 °C.

Examples:

• ◆ 30 °C corresponds to a resistance from 1500...2000 ω
• ◆ 80 °C corresponds to a resistance from 275...375 ω

If the specification is not obtained:

• ‒ Renew air mass meter (G70) with intake air temperature sender (G42) , item 2 .

Continuation of check when display = ambient temperature:

• ‒ Remove the intake hose between air mass meter and throttle valve control part.
• ‒ Note intake air temperature value in display zone 4.

• ‒ → Spray sender -arrow- with commercial chilling agent whilst observing the temperature value. The temperature value must
       decrease.
• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.