Volkswagen Workshop Service and Repair Manuals

Notes:

• ◆ A 5-character code must always be displayed during the control unit identification.
• ◆ Read measured value block 125 to see which control units are connected to engine control unit via data bus , Evaluating measured value block, display groups 120...129 -Communication.
• ◆ The control unit must be recoded if the vehicle relevant coding is not displayed or the control unit has been renewed.

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 with cable V.A.G 1551/3

Test conditions

• ● The coolant temperature should only be a maximum of 80 °C, =>display group 04, display zone 3

Work sequence

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (Connecting fault reader and selecting engine control unit .)

• ‒ Press keys 0 and 7 for the function "Code control unit" and confirm entry with Q key.

• ‒ Enter the relevant code number for this vehicle and confirm with Q key.

• Coding variations for engine control unit => Page 24-127 .

• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition and wait for control unit run-on to end (approx. 25 seconds).

Note:

The engine control unit doesn't store the entered code (shown on display) until ignition has been switched off and control unit run-on has ended (25 seconds). Incorrect coding could lead to:

• ◆ Engine running faults (gear change jerks, load change jerks, etc.)
• ◆ Increased fuel consumption
• ◆ Increased exhaust gas emissions
• ◆ Faults stored in fault memory which are not actually present
• ◆ Functions will not be performed (Lambda regulation, activation of the activated charcoal filter system, etc.).