Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
12 51 100 Replacing wiring harness section for ignition coil (N52)
Necessary preliminary tasks:
- Read out fault memory of DME control unit
- Switch off ignition
- Follow instructions for disconnecting and connecting battery
Disconnect battery negative lead from battery and lay to one side
- Remove FRESH AIR DUCT
- Remove ACOUSTIC COVER
- E65: Remove center of assembly compartment bulkhead.
Only: E60, E61, E63, E64
Unlock cover (1) with slide (3).
Unfasten screws (2).
Remove electronics box cover (1).
Only: E65
Release screw and remove holder (1).
Release screws and remove cover (2) from electronics box.
Release screws on seal (3).
Unlock plug on control unit and disconnect.
Unlock tab (1), pull contact carrier (2) in direction of arrow out of housing.
Unlock and disconnect all plug connections of ignition coil wiring harness section in electronics box.
Release screws and remove holder (1).
Tightening torque 12 52 1AZ .
Release screws and remove cable duct (1).
Installation:
Replace aluminum screws.
Tightening torque 12 52 2AZ .
| Work step | Note: |
|---|---|
| Unlock plug connections on ignition coils and disconnect | |
| Unlock plug on eccentric shaft sensor and disconnect | |
| Unlock plug on positioning motor for eccentric shaft and disconnect | |
| Unlock plug on both solenoid valves and disconnect | |
| Unlock plug on inlet and exhaust camshaft sensors and disconnect | |
| Unlock plug on A/C compressor and disconnect | |
| Unlock plug on oil pressure switch and disconnect | |
| Unlock plug on coolant temperature sensor and disconnect | |
| Disconnect connector strip from injection pipe | |
| Remove FRONT UNDERBODY PROTECTION | |
| Unlock plug on electrical coolant pump and disconnect | |
| Unlock plug on coolant thermostat and disconnect | |
| Disconnect engine ground connection |
Now clear the fault memory.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.