Audi Workshop Service and Repair Manuals

The following procedure applies to engine control units which are not bolted to a sheet-metal housing (to prevent theft). For procedure for engine control units with sheet-metal housing, refer to =>Page 24-40.

Removing

• ‒ Connect up vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Ignition must be on.

→ Control unit identification and code -2- appear on display of vehicle diagnostic, testing and information system VAS 5051.

• ‒ Always start by displaying control unit identification and printing it out.
• ‒ Switch off ignition.

• ‒ → Pull off rubber seal of plenum chamber cover in direction of arrow.
• ‒ Detach plenum chamber cover -1- to front.

• ‒ → Use screwdriver to prise off the two caps -3-.
• ‒ Slacken off hexagon nuts -4- by several turns.
• ‒ Detach wiper arms -2- from wiper shaft by tilting slightly.
• ‒ Completely unscrew hexagon nuts and detach wiper arms.
• ‒ Pull off securing clips -1- and detach cowl panel grille -5-.

• ‒ → Remove cover for electronics box in plenum chamber -arrows-.

• ‒ → Use screwdriver to prise off securing strap -arrows-.

• ‒ → Release catches -arrows- and unplug connectors -1- and -2- of engine control unit.
• ‒ Take out engine control unit.

Installing

Install in reverse order, paying attention to the following:

The following steps must be performed after connecting new engine control unit:

• ‒ Activate engine control unit in "Assisted fault-finding" under diagnosis item "Replacing engine control unit".

Use is to be made for this purpose of vehicle diagnostic, testing and information system VAS 5051.

Procedure for replacing engine control unit versions which are bolted to a sheet-metal housing (to prevent theft)

Removing

• ‒ Connect up vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" from list. Ignition must be on.

→ Control unit identification and code -2- appear on display of vehicle diagnostic, testing and information system VAS 5051.

• ‒ Always start by displaying control unit identification and printing it out.
• ‒ Switch off ignition.

• ‒ → Pull off rubber seal of plenum chamber cover in direction of arrow.
• ‒ Detach plenum chamber cover -1- to front.

• ‒ → Use screwdriver to prise off the two caps -3-.
• ‒ Slacken off hexagon nuts -4- by several turns.
• ‒ Detach wiper arms -2- from wiper shaft by tilting slightly.
• ‒ Completely unscrew hexagon nuts and detach wiper arms.
• ‒ Pull off securing clips -1- and detach cowl panel grille -5-.

• ‒ → Remove cover for electronics box in plenum chamber -arrows-.

• ‒ → Use screwdriver to carefully prise off securing strap -arrow-.

Note:

Item -1- in illustration shows engine control unit with anti-theft housing.

→ To render access to connectors at engine control unit more difficult (anti-theft protection), engine control unit -1- is bolted by way of a catch -2- and shear bolts -3- to a sheet-metal housing -4-.

Locking fluid is applied to thread of shear bolts to make bolts more difficult to screw out.

Engine control unit must be separated from sheet-metal housing to unplug connectors from engine control unit (e.g. when connecting up test box or replacing engine control unit). This procedure is described in the following.

Tools required:

• ◆ → Hot-air blower -1- (from wiring-harness repair set VAS 1978)
• ◆ Nozzle attachment -2- (also from wiring-harness repair set VAS 1978)
• ◆ Commercially available gripping pliers

Procedure:

• ‒ → Tilt engine control unit with anti-theft housing towards engine compartment so that catch (item -2- in Fig.) becomes visible, placing a clean cloth beneath engine control unit with anti-theft housing.

• ‒ → Make settings on hot-air blower as shown in illustration, i.e. set temperature potentiometer -2- to max. heat output and two-stage air flow switch -3- to position 3.

Note:

Then use hot-air blower to heat thread of catch, into which shear bolts are screwed. This operation is designed to reduce the inhibiting action of the locking fluid on the shear bolt thread to make it easier to screw out the shear bolts afterwards.

• ‒ → Move nozzle -1- of hot-air blower towards thread of catch such that nozzle "surrounds" thread. Allow nozzle to rest on upper end of sheet-metal housing.
• ‒ Switch on hot-air blower and heat thread for roughly 20 to 25 seconds.

• ‒ → Then grasp head of bolt -2- with gripping pliers -1- and screw out shear bolt in direction of arrow.

Employ exactly the same procedure for the second shear bolt, taking particular care to avoid the control-unit connectors in the immediate vicinity.

• ‒ → Move nozzle -1- of hot-air blower towards thread of catch again such that nozzle "surrounds" thread. Allow nozzle to rest on upper end of sheet-metal housing.
• ‒ Switch on hot-air blower and heat thread for roughly 20 to 25 seconds.

• ‒ → Then grasp head of bolt -2- with gripping pliers -1- and screw out shear bolt in direction of arrow.

Engine control unit can now be separated from sheet-metal housing.

• ‒ Release connectors of engine control unit and unplug.
• ‒ Take out old engine control unit and insert new one.

Installing

Install in reverse order, paying attention to the following:

The following steps must be performed after connecting new engine control unit:

• ‒ Activate engine control unit in "Assisted fault-finding" under diagnosis item "Replacing engine control unit".

Use is to be made for this purpose of vehicle diagnostic, testing and information system VAS 5051.