12 63 520 Replacing master relay (M51, M52, M62)

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 BMW 540i, 2002 BMW 540i, 2001 BMW 540i, 2000 BMW 540i, and 1999 BMW 540i. However, it is still accessible from the selected car via links, so may be relevant.

Switch off ignition.

Fold open locking bracket (1).

Remove rubber gasket (2).

Fig 1: Removing Rubber Gasket

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Remove retaining clip (3).

Pull filter housing (4) upwards to remove.

Fig 2: Pulling Filter Housing Upwards

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Unscrew bolts (1).

Tightening torque, refer to 12 90 4AZ in ENGINE ELECTRICAL SYSTEM - TIGHTENING TORQUE .

Fig 3: Identifying Bolts

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M52, M62:

Master relay in Digital Motor Electronics
Engine fuses for Digital Motor Electronics

Fig 4: Identifying Master Relay In Digital Motor Electronics

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Notes on troubleshooting:

If the starter cranks the engine during the starting sequence but the engine fails to fire, check the engine fuses and, if necessary, replace them entirely along with the fuse holder.
Search for cause of melting of fuses.