Volkswagen Workshop Service and Repair Manuals

Servicing ignition part:

=> Repair group 28

Notes:

• ◆ The engine control unit is equipped with self-diagnosis. Before carrying out repairs and fault finding the fault memory must be interrogated. Also the vacuum hoses and connections must be checked (unmetered air).
• ◆ Components marked with * are checked via the self diagnosis
  , interrogating and erasing fault memory.
• ◆ Components marked with **can be checked with the final control diagnosis => Page 01-24 .
• ◆ Disconnecting and connecting the battery must only be done with the ignition switched off, otherwise the engine control unit could be damaged.
• ◆ For trouble-free operation of the electrical components a voltage of at least 11.5 V is necessary.
• ◆ If the engine starts, runs for a short period and then stops, after fault finding, repairs or component tests, then the fault may lie with the immobilizer which is blocking the engine control unit. The fault memory must be interrogated and if necessary the control unit matched => Page 24-68 .
• ◆ Do not use sealants containing silicone. Particles of silicone drawn into the engine, will not be burnt in the engine and damage the Lambda probe.
• ◆ During some checks it is possible that the control unit will recognise and store a fault. Therefore after completing all checks and repairs the fault memory must be interrogated and if necessary erased.
  => Page 01-6 , interrogating and erasing fault memory
• ◆ The "learnt" values will be erased if the control unit is disconnected from the current supply. Engine running problems may occur until the control unit has "relearnt" all values.
• ◆ Always renew spring-type hose clips with screw-type hose clips.

Safety precautions

Rules for cleanliness => Page 24-20

Technical data => Page 24-21

Checking intake system for leaks (unmetered air) => Page 24-81