While the ignition coil in your BMW can last well over 140,000 miles, some factors such as heat and vibrations from your engine can cause the accelerated wear of the coil. This results in the failure of the coil, causing you to need a replacement earlier than usual.
The ignition coil is also known as the compact electrical transformer. It is responsible for converting the battery’s low volt currents into a much higher voltage needed to ignite the fuel/air mixture required for powering the engine.
Although ignition coils are designed to last for an extended period, heat and vibrations from your BMW engine can cause damage to the coil housing, causing it to fail. When the coil fails, you may experience difficulty starting your car or repeated stalling, reduced fuel efficiency, rough idle, engine misfire, or power loss.
The failure of the coil will undoubtedly affect your vehicle’s overall performance and, in extreme cases, might cause your vehicle to break down. Hence, knowing the indicators of a failing ignition coil will go a long way in helping you prevent the breakdown of your vehicle.
Symptoms of a Failing Ignition Coil
- Decreased Fuel Economy: When your ignition coil malfunction, it fails to provide the sufficient spark needed. Your vehicle tries to compensate for the insufficient transfer of power between the battery and the spark plug by sending more fuel than usual to the engine. This causes your vehicle to consume more fuel. Whenever you notice increased fuel consumption, you may want to check out your ignition coil.
- Illuminated Check Engine Light: A faulty ignition coil will cause your engine to misfire, triggering your check engine light. While other factors could have triggered the check engine light, a faulty ignition coil cannot be ruled out as the cause. You should visit a mechanic immediately to help you examine what triggered the check engine light to prevent irreparable damage to your engine.
- Engine Misfiring, Rough Idle, and Power Loss: Since the ignition coil is responsible for providing the needed spark required to ignite the fuel/air mixture, its failure will cause the engine to misfire. Your engine may also idle roughly where it feels like your vehicle is about to break down or lose power.
- Engine Stalling: Engine misfire and power loss can cause your engine to stall or, in some cases, completely stop the engine. While restarting your engine might work at times. Other times, your vehicle may fail to start, thereby leaving you stranded.
- No Start Condition: A failing ignition coil won’t send enough spark needed to ignite the fuel/air mixture. When the problem gets worse, the spark may not be enough to start the combustion cycle in your engine. When you get to this level, the ignition coil will need to be replaced.
While all these signs point at a faulty ignition coil, it’s best to have the problem diagnosed by an experienced mechanic before making any conclusions.
Causes of Ignition Coil Failure
Your ignition coil may fail for several reasons, and they include:
- The Position of the Ignition Coil: Although the coil is insulated, its location close to the engine exposes it to heat and vibrations from the engine. This causes damage to the coil housing over time, which results in the coil failure. Also, modifying your vehicle performance can significantly accelerate the wear of the coil.
- Excessive or Inadequate voltage supply: Either case will cause the failure of the coil. While an insufficient voltage supply to the coil affects its effectiveness, the excess voltage can damage it. The excessive or inadequate voltage supply can be attributed to a weak battery, faulty cables, or a faulty spark plug.
- Other reasons include overheating coil, excess moisture caused by oil leaks, contact faults, heat exposure, etc.
Motor Cars International, Leaders In European Auto Maintenance & Repairs
The excellent performance European vehicles deliver depends on the quality of service they receive. Sticking with your vehicle’s maintenance program will 
go a long way towards ensuring its performance and durability. At Motor Cars International, we understand how vital even basic service appointments are for your vehicle.
Our ASE-certified mechanics employ the latest factory-grade tools and equipment to ensure quality service. For decades, we have been helping residents throughout Bridgewater, MA and surrounding areas of Easton, Norton, Raynham, and Sharon. Please call or visit our shop today to schedule an appointment or learn more about our services and maintenance programs.