Is Your Ignition Coil Failing?

The BMW X5 enters its third generation with more power, more room and a more refined design. As a mid-size crossover, the X5 is at home both on road and off road. Featuring optional dynamic performance control, it allows distribution of power to the rear axle. Active roll stabilization reduces body roll and gives the X5 superior handling. Besides having plenty of rear room and comfortable seats, the X5 also has one of the largest cargo areas offered by BMW. With the seats folded, the cargo space measures nearly 77 cubic feet. The luxury crossover debuted in 1999 and its latest generation began production in 2013.

Symptoms of Ignition Coil Failure

Ignition coils are part of your X5's ignition system and are considered a component of your electronic engine management system. The ignition coil works as an induction coil that has the job of converting your car's 12 volt system into the thousands of volts necessary to get across the spark plug gap and ignite the air-fuel mixture that starts your engine. Older ignition coil systems use only one coil to give all of the cylinders spark. However, the newer systems have one coil per cylinder. Since the ignition coil has the job of providing your engine spark, it's not surprising that failure of the coil or coils has an effect on engine performance. The following are common symptoms of ignition coil failure.

1.Rough engine performance is one of the more common signs of a faulty coil or coils. Problems can include misfiring, rough idling and power loss. Ignition coils are one of the most important components in the ignition system and that's why loss of engine performance is one of the top signs of worn or failing coils.

2.Check engine light comes on. The check engine light can come on for a variety of reasons, depending on the vehicle. When you have a faulty ignition coil or coils, it can cause misfires, which will usually always trip the check engine light. If a coil burns or shorts out, that will also cause the computer to illuminate the check engine light. If you see this light and are having engine performance issues, it's important to get your car scanned for trouble codes.

3.Car doesn't start. If you have a faulty ignition coil or coils, it's possible that your car won't start at all. If you have a vehicle that only uses one coil, this is even more likely. Remember that your ignition coil is responsible for producing spark. If there's no spark, your engine won't start. In the case of a failing coil, or an engine with multiple coils, you might experience difficulty starting your car, which coincides with the difficulty the coils are having producing spark.

Testing an Ignition Coil

If you have one or more of the aforementioned symptoms and want to test your ignition coils, then there are a few ways to do this. Ignition coils are basically high voltage transformers. They are, in fact, quite reliable, but like any other part, can wear out over time through exposure to heat and other elements in the engine's unfriendly environment. There are two main ways to test your ignition coils. One is the spark plug test and the other is the bench test. The former is generally the most effective, but the latter is more thorough. The reason for this is that the latter test will show even minor coil damage, i.e. damage that might not be producing any significant symptoms. If you decide to do the spark plug test, the first step is to remove the wire from the plug. Then, use a spark plug socket to remove the plug. If you're doing the bench test, then consult your manual to find out how to remove the windings from your ignition coil. Once you've removed the spark plug, put the plug wire back in. Hold the wire with insulated pliers and touch the bare end of the plug to a ground. This can be any exposed metallic surface. Have someone else turn the key to start the car at this time. When the key is turned, you should see a blue spark appear at the end of the plug. If you see this, then your coil is, at least, not majorly damaged. If you don't see a spark, then your coil needs to be replaced. Again, a faulty coil may still produce spark, so if you still suspect that your ignition coil is in trouble, then you will need to do the bench test to be sure. Going back to the windings you removed. You now need to check your manual for accurate resistance readings on your particular vehicle. Usually the primary winding will have a reading somewhere between 0.75 and 0.81 Ohms and the secondary between 10,000 and 11,000. Attach a multimeter to the primary winding's two outside poles. For the secondary, attach it to one of the side poles and then to the central high tension terminal. If you get readings that are even a little bit outside of what your resistance readings should be, then you need to replace your coil.

Ignition Coil Replacement

In the event that your ignition coils need to be replaced, it's important that you also check your spark plugs. Bad spark plugs can cause coils to operate at a higher level than they're designed for. A faulty ignition coil could be the result of one or more bad plugs. Replace any bad plugs at the same time as your coils. Visit to find a wide selection of OEM BMW parts, including the X5 ignition coil. It's easy to find what you want on our site, just enter a VIN, part number or keyword in the search bar, or browse by vehicle. Get the best fit and better reliability by using only OEM BMW parts for all your repairs, replacements and upgrades. Contact our BMW parts experts if you have any questions or need help finding the right part for your BMW.