Removal and installation / checking of ignition coils (BMW 5 Series E39)

You can check the ignition coils using an ohmmeter. However, an accurate check that allows you to make confident conclusions about certain faults in the ignition system can only be performed at a service station using an oscilloscope.

Removal

Turn off the ignition.



Remove the mounting bolt caps and unscrew the 2 bolts located underneath them.

Remove the oil filler cap and cylinder head trim.



Remove the plug from each ignition coil by pulling the metal clip on the plug upwards.



Loosen the 2 mounting bolts for each coil and remove the coils.

Note: Ignition coils of cylinders 1 and 8 have flexible jumpers. Grounds "3" with the cylinder head cover.

If there is a metal cylinder head lining: a flexible ground jumper from the wire shaft is located between cylinders 2 and 3.

If there is a plastic cylinder head lining: the mass wire "1" is attached to the connecting plate "2", see the figure. During installation, the wires must be attached again in their original places.

Examination

Measure the resistance of the primary winding of the ignition coil by connecting an ohmmeter to contacts 1 and 15. The prescribed resistance value is approximately 0.8Ω.

Note: Secondary winding resistance (between the spark plug connector, pin 4 and ground connection) not measured.

Replacing the spark plug tip is described here.

Installation

Insert the coils with spark plug tips and connect them with flexible jumpers.

Secure the plugs to the ignition coils using metal clamps.

Install the cylinder head trim. Screw on the oil filler cap.