Volkswagen Workshop Service and Repair Manuals

Special tools, 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 1598/18
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test sequence

• ‒ Connect fault reader V.A.G 1551 and select engine electronics control unit (address word 01); selection is carried out with engine idling.
  

• ‒ Input 08 for "Read measured value block" function and confirm with Q.

• ‒ Press keys 0, 0 and 7 for "Display group number 7" and confirm entry with Q key.

• ‒ Observe display in display zone 3.

If faulty the following substitute values will be displayed:
     Engine code 1Z, AHU: 18.9 °C
     Engine code AFN: 136.8 °C

• ‒ If no realistic value is displayed in display zone 3 or the substitute is displayed. Check intake manifold temperature sender and wiring to sender as follows:

Electrically checking intake manifold temperature sender (G72)

• ‒ Switch off ignition.
• ‒ Pull connector off sender =>Fitting locations overview, Page 23-4 .

• ‒ → Carry out resistance measurement between contacts using hand multimeter V.A.G 1526.

• ‒ → Specifications =>Illustration

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 attained:

• ‒ Replace intake manifold temperature sender (G72).

Checking wiring connection to intake manifold temperature sender (G72)

• ‒ Switch off ignition.
• ‒ Pull connector off sender =>Fitting locations overview, Page 23-4 .
• ‒ Connect test box .

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

• ‒ → Wiring from connector contact 2 to test box socket 33.
• ‒ Wiring from connector contact 1 to test box socket 64.
• ‒ Rectify any open/short circuit as necessary.
• ‒ If neither an open or short circuit exists, renew Diesel direct injection system control unit.