Removing and installing prewiring for unit injectors — VW
Removing and installing prewiring for unit injectors on VW: factory workshop procedure for engines AXB, AXC, BDJ, BJB. Full factory text, tools and checks.
Workshop procedure for VW — the factory write-up, straight from real workshop data.
📋 Procedure
ℹ️ Torque figures below come verbatim from workshop data — always cross-check against your vehicle's factory manual before final tightening.
Removing and installing prewiring for unit injectors
Special tools and workshop equipment required
Puller
T10312
Wrench
T10310
Removing
Caution
Removal and installation of the pre-wired wiring harness may only be undertaken by unscrewing the clips. Releasing the cable guide from the clips bends the clips which may break the cables due the excessive play. This also applies when changing the unit injectors and all work which does not require the central connector to be completely removed.
Note
Disconnecting connectors on piezo unit injectors may only be undertaken using special tool puller
T10312.
Remove engine cover panel.
To do this, pull engine cover panel upwards abruptly at front arrows A and then pull forwards out of rear fastening arrow B.
Remove cylinder head cover (see the separate procedure).
Disconnect central connector on cylinder head.
Fit special wrench
T10310 on adapter ring and release it by turning key through 90° ( (1)
/ (4) turn) in direction of arrow.
Pull securing clip (1) slightly upwards with a screwdriver and press through central connector (2) inwards.
Slide the puller
T10312 onto the unit injector connector from the side and pull it off in direction of arrow
. Use long-nosed pliers for the older connector version.
Pull connectors off glow plugs (1)
. Unscrew securing bolts (2) of steel clips and remove complete pre-wired wiring harness.
Installing
Installation is carried out in the reverse order; note the following:
Route pre-wired wiring harness and tighten securing bolts.
Guide central connector through opening in retaining frame, ensure securing clips (arrows) are seated correctly when doing this.
Fit adapter ring (colour marked
“longer” stud (arrow) faces 12 o'clock)
Fit special wrench
T10310 on adapter ring and lock it by turning key through 90° ( (1)
/ (4) turn) in opposite direction of arrow.
Note
When adapter ring is installed correctly the colour marked
“shorter” stud faces 12 o'clock.
Fit central connector to cylinder head and lock in position.
Install cylinder head cover (see the separate procedure).
Fit engine cover panel.
Specified torques (see “Assembly overview - cylinder head”)
Component
Specified torque
Threaded connections for wiring harness.
10 Nm
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix → · How these pages are made →Workshop data on this page last updated 20 Sep 2026.