Volkswagen Workshop Service and Repair Manuals

Special tools, testers and auxiliary items

• ◆ Fault reader V.A.G 1551 with cable V.A.G 1551/3
• ◆ CO tester V.A.G 1363 A or 4 gas tester V.A.G 1788
• ◆ Adapter V.A.G 1363/3
• ◆ 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

Check conditions

• ● Idling adjustment OK.
• ● Exhaust system between catalyst and cylinder head free of leaks

Test sequence

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

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

• ‒ Input 01 for "Display group number" and confirm with Q.

Note:

If something different is indicated on the display:

=> Fault reader operating instructions

Only continue with the test when

• ● The coolant temperature is above 80 °C
  -Display zone 2-
• ● The engine has then run for a further 2 minutes at idling speed

• ‒ → Connect CO tester with adapter V.A.G 1363/3 to CO sampling pipe.
• ‒ Check CO content.
       Specification: 0.3...1.2 Vol.%
• ‒ Read off Lambda probe voltage in display zone 3. Voltage must fluctuate in the range
       0... 1.0 V

• ‒ → Pull 2 pin connector -1- off coolant temperature sender (G62) -2- . The probe voltage must
       increase
  and then drop back to the old control range.
• ‒ Reconnect connector. The probe voltage must
       drop back
  and then increase to the old control range.

Note:

The engine speed must not exceed 1500 rpm during the check, otherwise the connector disconnected from the control unit will be recognised as a fault.

• ‒ Press ⇒ key.

• ‒ Input 06 for "End output" and confirm with Q.
• ‒ Switch off ignition

If the specifications are not attained:

• ‒ Check Lambda probe heating => Page 24-62 .
• ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom.

• ‒ → Separate 4 pin connector to Lambda probe -1-.
• ‒ Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
       Contact 3+socket 42
       Contact 1+socket 20
       Wire resistance: Max. 1.5 ω
• ‒ Check wiring at 4 pin connector for short to one another.
       Specification: ∞ω
• ‒ Check screening -test box socket 65- for short to the probe wiring according to current flow diagram.
       Specification: ∞ω

If the specifications are not attained:

• ‒ Renew Lambda probe (G39).