Renewing diesel direct injection system control unit J248 (master control unit) — AUDI

🧭 Before you start

Fits: Audi A8 D3 (4E, 2002–2010)

• Renewed: shear bolts

Don't miss

• Connect vehicle diagnostic, testing and information systemVAS 5051B and select vehicle system "“01 - Engine electronics”" from list. When doing this, the ignition must be switched on.
• Always start by displaying the control unit identification and printing it out.
• The two shear bolts screwed into the control unit do not need to be heated. They should be removed without being heated.

🔧 Engine codes this applies to

📋 Procedure

1. Connect vehicle diagnostic, testing and information system VAS 5051B and select vehicle system "“01 - Engine electronics”" from list. When doing this, the ignition must be switched on.
2. Always start by displaying the control unit identification and printing it out.
3. Remove cover from plenum chamber (right-side).
4. ⚠ Heating the thread of the locking plate also heats up the shear bolts and parts of the metal housing. Take care to avoid burns. It is also important to ensure that only the thread is heated and none of the surrounding components if at all possible. These should be covered if necessary. — Select settings on hot air blower as shown in illustration, i.e. set temperature potentiometer (2) to maximum heat output and two-stage air flow switch (3) to position 3.
5. Apply heat to the threads of the shear bolts on the connector side as shown in the illustration for approx. 25 to 30 seconds.

6. ⚠ Heating the thread of the locking plate also heats up the shear bolts and parts of the metal housing. Take care to avoid burns. It is also important to ensure that only the thread is heated and none of the surrounding components if at all possible. These should be covered if necessary. — Unscrew shear bolts using mole grips (see arrow in illustration).
7. The two shear bolts screwed into the control unit do not need to be heated. They should be removed without being heated.
8. Detach metal locking plate from control unit connectors.
9. Remove two bolts securing diesel direct injection system control unit J248 (master control unit) and pull control unit forwards.
10. Release connectors on diesel direct injection system control unit J248 and unplug connectors.
11. Take out old diesel direct injection system control unit J248 and install new control unit. [Note: Installation is performed in the reverse sequence. After installation, the locking plate must be re-fitted on the control unit. Use new shear bolts. After renewing the engine control unit you must also adapt the injector delivery calibration values for the new engine control unit (injector delivery calibration values influence engine power output and exhaust emissions).If only the master control unit (diesel direct injection system control unit J248) is renewed, the following injectors must be re-adapted: cylinders 1, 4, 6 and 7.]
12. Activate engine control unit in "“Guided Functions”" mode, "“Renew engine control unit”".

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