Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ 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 1598/18
• ◆ 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 fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the ignition must be switched on.
  (Connecting fault reader and selecting engine electronics control unit .)

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

• ‒ Press keys 0 and 2 for "Display group number 02" 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 when display = approx. 5 °C or 20 °C:

• ‒ Switch off ignition.

• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

Engine codes ADY and AGG

• ‒ → Pull 2 pin connector -1- off intake air temperature sender (G42) -2-.

• ‒ → Check wiring between test box and 2 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 37
       Contact 2+socket 29
       Wire resistance: Max. 1.5 ω

Engine code AFT

• ‒ → Pull 2 pin connector -1- off intake air temperature sender (G42) -2-.

• ‒ → Check wiring between test box and 2 pin connector for open circuit according to current flow diagram.
       Contact 1+socket 37
       Contact 2+socket 35
       Wire resistance: Max. 1.5 ω

Continued for all engine codes

• ‒ Check wire between control unit connector and 2 pin connector contact 2 for short to wire contact 1 and to vehicle earth, according to current flow diagram.
       Contact 2+socket 37
       Specification: ∞ω
• ‒ Check wire between control unit connector and 2 pin connector contact 2 for short to wire contact 1 and to vehicle earth, according to current flow diagram.
       Contact 2+socket 37
       Specification: ∞ω
• ‒ Additionally check wiring for short to battery positive.
       Specification: ∞ω

If no fault in wire is detected:

• ‒ Perform resistance measurement on intake air temperature sender (G42) contacts 1+2, resistance figures => Page 24-30 , Fig. 1

If the specification is not obtained:

• ‒ Renew intake air temperature sender (G42)
  , item 18 .

Continuation of check when display = ambient temperature:

Engine codes ADY and AGG

• ‒ → Remove intake air temperature sender G42) (plug remains connected).

Engine code AFT

• ‒ → Remove intake air temperature sender G42) (plug remains connected).

Continued for all engine codes

• ‒ Note intake air temperature figure in display zone 4.
• ‒ Spray sender with a commercial chilling spray and at the same time observe the temperature figure. The temperature figure must
       decrease.
• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.