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.
Replacing negative battery lead (Except M4 Convertible)
Comply with notes on BATTERY ELECTRONICS .
Removal:
Open flap (1) and remove.
Slacken nut (1) on negative terminal (2).
Detach negative terminal upwards, lay to one side and secure.
Release nut (3) and remove battery earth lead (4).
Installation:
Join battery earth lead (4) on ground point and tighten with nut (3).
Tightening torque 61 21 6AZ .
Join negative terminal (2) on negative battery terminal and tighten with nut (1).
Tightening torque 61 21 1AZ .
Close and lock flap (1).
NO RELATED
Use the Manual With the Right Hardware
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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.