SEAT 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

Check conditions

• ● Coolant temperature at least 60 °C
• ● Exhaust system between catalyst and cylinder head free of leaks

Functional check

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and with the "Address word" 01 select the engine electronics control unit. When doing this the engine should be idling.
  (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 1 for "Display group number 01" and confirm entry with Q key.

Only continue with the test when the coolant temperature in display zone 2 exceeds 60 °C.

• ‒ Press C key.
• ‒ Press keys 0 and 5 for "Display group number 05" and confirm entry with Q key.

• ‒ Check operating condition of Lambda control in display zone 4:

Lambda control operating condition display:

• ◆ Lambda control on stop:

• 5th position from right must display 0
      Display:: 00000000

• ◆ Lambda control active:

• 4th position from right must display 1
      Display: 00001000

• ◆ Fault in fault memory:

• 3rd position from right must display 0 (no fault in fault memory)
      Display:: 00000000

• ◆ Lambda probe operationally ready:

• 2nd position from right must display 1
      Display: 00000010

• ◆ Mixture:

• 1st position from right must display 0 and 1 alternately
      Display: 00000001 (1 = rich mixture)
      Display: 00000000 (0 = lean mixture)

• ‒ Press C key.
• ‒ Press keys 0 and 1 for "Display group number 01" and confirm entry with Q key.

• ‒ Observe Lambda probe voltage in display zone 3. The voltage must fluctuate
      at least 10 times per minute
  in the range
      0...1.1 V.

If the probe factor does not fluctuate as stated:

• ‒ Carry out road test and burn Lambda probe clean and repeat check.

If the specifications are not obtained again:

• ‒ Check Lambda probe heating => Page 24-33.

If the displayed figure remains constant:

• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Continue check according to following table.

If the specifications for Lambda control operating conditions are not attained or the probe voltage does not fluctuate as stated:

Checking Lambda probe wiring

• ‒ Remove dash panel insert.

=> Electrical system; Repair group 90

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

• ‒ → Separate 4 pin connector to Lambda probe (G39) -arrow-.

• ‒ → Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
      Contact 3+socket 42
      Contact 4+socket 17
      Wire resistance: Max. 1.5 ω
• ‒ Check wiring at 4 pin connector for short to one another according to current flow diagram.
      Contact 1+socket 20
      Contact 1+socket 42
      Contact 1+socket 17
      Contact 2+socket 42
      Contact 2+socket 17
      Contact 3+socket 17
      Specification: ∞ω
• ‒ Check screening -test box socket 21- for short to the probe wiring according to current flow diagram.
      Contact 2+socket 21
      Contact 3+socket 21
      Contact 4+socket 21
      Specification: ∞ω

If the specifications are not attained:

• ‒ Check wiring connections according to current flow diagram.

If no wiring fault is detected:

• ‒ Renew Lambda probe (G39).