Removing and installing engine control unit J623 with theft protection — VW

🧭 Before you start

Fits: VW Jetta VI (16, 2010–2018), VW Golf V / Jetta (1K, 2003–2009); platform code AJ5

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• Observe applicable safety precautions during road test .

🔧 Engine codes this applies to

📐 33 workshop diagrams for CBDA

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Switch off ignition.
2. Remove wiper arms Electrical system92Windscreen wiper system; Removing and installing wiper arms.
3. Remove plenum chamber bulkhead General body repairs50Body - front; Plenum chamber bulkhead.
4. Press retaining frame down in (direction of arrow) and remove engine control unit.
5. Unscrew shear-head bolts (arrows) using pliers.

6. Insert screwdriver between both locking plates (arrow).
7. Carefully press screwdriver in direction of (arrow) and bend retaining bow (1) upwards at the same time.
8. Bend retaining bar (1) in direction of (arrow) until it can be pulled off connectors.
9. Push connector locking devices in direction of (arrow), and pull connectors off.
10. Fit connectors to engine control unit and slide locking devices onto stop in direction of (arrow).
11. Fit retaining bow (1) onto connectors and press it in direction of (arrow).
12. Guide pin (2) to stop into hole on valve timing housing.
13. Secure retaining bow with shear-head bolts to engine control unit (arrows).
14. Tighten shear-head bolts evenly until heads shear-head off (arrows).
15. Insert engine control unit into retaining frame and press retaining frame upwards in (direction of arrow)
16. Install plenum chamber bulkhead General body repairs50Body - front; Plenum chamber bulkhead.
17. Install wiper arms Electrical system92Windscreen wiper system; Removing and installing wiper arms.
18. If engine control unit has been renewed, connect vehicle diagnosis tester and perform the "“Guided function; Renewing engine control unit”".
19. Read fault memory of engine control unit and erase all fault entries "“Guided functions”".
20. Carry out a road test. [Note: Observe applicable safety precautions during road test .]
21. Read fault memory of engine control unit again.

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