If you’re reading this because you’re concerned that your ignition coil is failing, then you’ve come to the right place. Our mechanics have come together to provide you with the best explanation for why one or more of your ignition coils are failing and what you can do to resolve it. So, let’s dive into the purpose of your BMW’s ignition coil.

An ignition coil is the part of your engine which powers the spark plug. It’s connected to a distributor, which helps time the combustion of your engine’s cylinders. Timing in an engine is essential. Without the properly-timed spark created by a spark plug to an ignition coil, a cylinder will misfire. Misfires damage your engine and decrease the overall performance of your BMW.

There’s an ignition coil for each cylinder in your BMW. If one fails, then your Engine Control Module (ECM) will shut off power being routed from your distributor into the faulty ignition coil.

We want you to understand that faulty or failing ignition coils should be repaired as soon as possible. As time progresses, your engine will suffer from future misfires and overcompensation for the loss of power.

What causes ignition coils to fail?

Because the opening of your BMW’s ignition coils are so close to the engine, heat and vibration can cause damage to the housing of the coil over time. Most BMW ignition coils last for more than 140,000 miles. If you frequently push your car’s performance, the lifespan of your coils can decrease significantly. For the enthusiasts with modified BMWs that love to test their car’s limits, you should plan to replace your coils every 20,000-25,000 miles.

Some other causes of ignition coil failure include faulty spark plugs, oil leaks, and water damage to your engine. A faulty spark plug may not conduct electricity properly. This could cause the coil housing to melt over time from the excess heat generated on the insulator side. Oil leaks will damage the connection between the coil and spark plug, lowering conductivity and in turn preventing a spark. Lastly, water damage will surely short the circuit created from the ignition coil to spark plug connection.

Signs of a Failing Ignition Coil

You may have already noticed some or more of these symptoms, which has brought you here to learn more about them. Even if you haven’t experienced ignition coil failure yet, you should always be mindful of the symptoms. Here are some signs of a failing ignition coil:

• Cylinder Misfire. The ignition coil is responsible for powering the spark conducted through your spark plugs. A failing coil will cause untimed sparks or no spark at all, depending on the severity of damage.
• Power Loss. With one or more cylinders firing off timing or not at all, your engine’s rhythm is thrown out of whack. This is what causes performance issues in your BMW when the coil is faulty. Each cylinder is synchronized to fire at a set time in a rotation. One cylinder firing out of timing greatly affects your engine’s efficiency.
• Rough Idling. For the same reason as a loss in power, your engine will violently shake when idling. This happens because the functioning cylinders are compensating for one or more cylinders failing to power your crankshaft’s rotation.
• Lower Fuel Economy. Are you visiting the gas station more often? Your ignition coil is likely the culprit. A faulty ignition coil doesn’t provide adequate spark for the combustion reaction in one of your cylinders. As the still-functioning cylinders compensate for the non-functioning cylinder(s), they burn much more gas than what your car normally should.
• Engine Stalling. Misfires and power loss will cause your car to suddenly stall and can even stop the engine entirely. One bad rotation and your engine will lose the momentum which powers it. You’ll have to restart the engine or be stranded because your engine won’t start.
• Starting Problems. Your car needs a spark to fire the cylinders and get the engine running. No spark means no combustion in the cylinder and an engine that won’t start.
• Check Engine Light. A faulty ignition coil that causes a misfire will surely signal your BMW’s computer that an issue is present in the engine. A code reader will pinpoint the exact cylinder being affected.

Tanner Motors: Your BMW Specialists

We advise you bring your BMW into our shop so we can give you the details of a proper inspection with our diagnostic tools. With some of the most certified technicians in Phoenix, AZ, Tanner Motors guarantees our skilled mechanics are ready to bring you the best service around. Call today to schedule a service.