Replacing the coil packs on your BMW is one of the easiest repairs you can do yourself to save money and avoid a trip to the repair shop. In fact, I recently shared an invoice from BMW detailing the ignition coil replacement cost in my E39 that the previous owner had paid for. Often times a failing coil pack will cause symptoms such as: rough idle, poor fuel economy, stumbling acceleration, and will turn on the service engine soon light.
The first step to diagnosing a bad coil pack is to use an OBD-II pocket scan tool such as this one to pull the diagnostic code that’s signaling your service engine soon light. These little scan tools are a must have for any BMW owner- I keep one in the map pocket in the door of my car at all times. After retrieving the code, you can now determine which exact coil is misfiring on a specific cylinder number.
While you can replace just that one failed coil pack, it is a good idea to consider replacing the entire set if they have high mileage or are original to the car. For example, if a car has 100k miles on all-original coil packs, I would definitely suggest ordering a full new set of coils and spark plugs. If the car had a service record of coil packs being replaced within the last few years, it would be acceptable to just replace a single coil that may have failed prematurely.
Do note that it’s important to also change the spark plug on the cylinder which had the bad coil. Driving with a weak spark for X number of miles can wear down and damage that plug’s sensitive electrode, so it is a good idea to replace that plug with the same one that came out of the car. Be sure not to mix different types of spark plugs into the car.
I’ve created this step by step video guide to show you how to replace the coil packs on your BMW. There are several different types of coils across the BMW models over the years, but for the most part, the process is nearly identical. For example, most models from 1992 through 2003 have coil packs which are held in place with two 10mm bolts. Around 2004 the coil packs updated to a newer version that install simply by clicking into place, so no more bolts are present. Generally speaking, this difference is minor and the video below should get you to the finish line.