BMW E60 glow plug relay and glow plug controller: fault and replacement

When the code comes from all the glow plugs at once, the fault is usually in the glow plug relay or its power cable, not the glow plugs. Check the power cable connector first: if it has melted or burned, the contact is poor and the cable should be replaced. If the code concerns only one glow plug, the fault is probably in that plug.

1. Remove the plastic cover on top of the engine. 2. Carefully disconnect the glow plug relay connectors. The lock is fragile and can break. 3. Undo the relay's two mounting nuts or bolts and fit the new one. The relay is on the side of the block under the intake manifold, but the intake manifold does not need to be removed. The job takes from under an hour to a couple of hours if the connector resists.

A faulty control relay can also destroy new glow plugs, so it is best to replace the relay and the glow plugs together. If the new relay does not help and the codes return immediately, the cause is often still a melted power connector, in which case the whole power cable is replaced.

No. The car does not go into limp mode and no message appears on the display; the fault only shows on a diagnostic tool. In practice the fault is noticed in frost, when starting becomes difficult.