5 Signs of a Faulty Ignition Coil

Each time a spark plugs in your car’s engine ignites the fuel, the electricity for the spark is delivered by an ignition coil. These remarkable components convert the battery’s meager 12-volt power into a massive 25,000 to 45,000 volts for the spark plugs. If one of your coils malfunctions, the corresponding cylinder will stop firing, causing a variety of engine problems. Here’s how to know when it’s time to visit your local Subaru dealer for a new coil. 

5 Signs of a Faulty Ignition Coil

If a vital component inside the engine fails, the check engine light will usually appear on your dashboard. This warning light might not specifically point to the faulty part, but with a bad coil, you’ll also experience the following problems:

Misfiring Spark Plugs

Your engine will start to sputter and shudder when a spark plug fails because of a malfunctioning coil. This misfiring will usually worsen when the car is idling, such as when waiting at traffic lights or slowing down to park. 

Trouble Starting Your Car

Without all cylinders firing at full power because of a bad coil, your car might have trouble starting. Cold winter mornings will pose a particular challenge for an engine with a bad coil. 

Plummeting Engine Power

A healthy engine requires all spark plugs to ignite the fuel at full capacity. If one or more of your coils fails to deliver the required voltage, your engine will have less power than usual. You might notice this when attempting to accelerate rapidly or when driving at higher speeds on the highway.

Lessened Gas Mileage

With a less efficient engine, a bad coil will also cause your fuel economy to drop. As a result, you’ll find yourself stopping more frequently to refill the tank. 

Smoke and Backfiring

Misfiring coils and spark plugs can lead to a cascade of other problems if not quickly repaired. As unburned fuel builds up inside the misfiring cylinder, it can start to leak back into the exhaust pipes. 

Inside the exhaust system, the fuel can suddenly ignite, causing backfiring and smoke to billow from your tailpipe. On occasion, this unspent fuel can even destroy the catalytic converter. 

Your Subaru Dealer Can Repair or Replace Your Bad Coils

If you suspect a bad coil, bring it along for our technicians to inspect right away. We might be able to clean or repair it. Alternatively, we can install a new coil and promptly restore your engine to good working order.

Visit Subaru Superstore of Surprise in Surprise, AZ, today to have your faulty coils fixed or replaced. At our full-service dealership, we strive to provide a consistently smooth and hassle-free vehicle buying, financing, and servicing experience, whatever your needs may be.