Bad Ignition Coil Symptoms and Replacement Cost

In this article, we are going to explain about information of ignition coil, so you will know the basic functions, bad symptoms, how to test, and also the average replacement cost. And here we are:

Basic Functions Of Ignition Coil

Ignition coils are known as compact electrical transformers. Their purpose is to take the low 12-volt current normally found in car batteries and convert it into a much higher voltage which is needed to ignite the fuel and start the engine. Each spark plug in a car has its own ignition coil. The coil is either physically connected to the spark plug with wires or it sits on top of the spark plug without using wires. The spark plug needs about 15,000 to 20,000 volts of electricity in order to form an electric spark that can ignite the fuel. If you don’t have strong ignition coils then it will result in weak fuel consumption or engine misfires.

Bad Ignition Coil Symptoms

If a vehicle is behaving intermittently and is giving its driver some trouble in a smooth driving, then it could indicate that the ignition coil of that vehicle has gone bad. The symptoms may vary depending on the severity of the ignition coil failure. And here are some common symptoms of bad ignition coil:

  • Backfiring

The backfiring caused by your vehicle can indicate the symptoms of the ignition coil failure in its early stages. The backfiring occurs when the unused fuel in the combustion cylinders of the engine leave through the exhaust pipe. If this problem is left unaddressed, then it can result in the costly repairs which can unnecessary if not properly maintained. The backfiring problem can be detected by the emission of a black smoke through the exhaust pipe. The smell of gasoline in that smoke may also give away the ignition coil failure.

  • Fuel Economy

Another symptom for a faulty ignition coil is the affected fuel economy. If your vehicle is getting less mileage than it was before, then it could mean that the ignition coil failure has occurred.

  • Engine Misfiring

Engine misfiring will be seen in a vehicle whose ignition coils have failed. Trying to start the engine of such a vehicle will result in engine misfiring like coughing spluttering noise regularly. When driving at high speeds, jerking and spitting will be seen in the behavior of that vehicle. A vehicle with a failed ignition coil will also result its vibration when it is idling at a stop sign.

  • Vehicle Stalling

The ignition coil failure will also result in the stalling of that vehicle. This will occur because of the irregular sparks sent to the spark plugs by the faulty ignition coil. The vehicle may shut off completely when brought to stop leaving you with the trouble to restart it.

  • Engine Jerking, Rough idling, Poor Power

Another symptom is engine rough idling, jerking and hesitate even at accelerate, and you will feel poor power when you drive the car.

  • Engine light Code On / DTC on

Commonly the code is: P0351 (Ignition Coil – Primary/Secondary Circuit Malfunction). If the ignition coil has a malfunction, the engine light code in the combination meter will turn on, and you should use a scanner or diagnostic tool to check the malfunction.

  • Engine hard starting

This symptom will occur especially if your car uses a single coil. If the coil has a malfunction, it means the engine will be cranking without sparks inside all cylinders.

The Average Ignition Coil Replacement Cost

The cost of a new ignition coil depends on the make and model of the car. Some coils are as cheap as $75 while others cost in the $300 range. If you have the replacement professionally done then the labor costs will be between $50 and $100 per hour. Therefore, you can expect to pay at least $150 to $200 if you were to take your car into a professional automotive repair shop and have them replace your ignition coil for you.

Read also: Average Fuel Filter Replacement Costs

How to Test Ignition Coil

To run a test on an ignition coil, first turn off your car’s engine and open up the hood. Locate one spark plug and remove the spark plug wire from it. These wires typically start from the distributor cap and run to the spark plug. Use rubber gloves and insulated tools when working with these electrical components. Take a spark plug socket and remove the spark plug. Now reattach the spark plug to the spark plug wire. Use insulated pliers to hold the spark plug onto some metal part of the engine so that the threaded portion of the spark plug is touching the metal. Remove the fuel pump and get ready to crank that engine. You may need an extra person to turn the key in the ignition because you are holding the spark plug down with the pliers. Once the engine is cranked, look for blue sparks forming along the spark plug gap. If you see blue sparks then your ignition coil is working properly. If you don’t see the sparks or if you see orange sparks then this is a sign of the ignition coil malfunctioning. When you’re done with the test, disconnect the spark plug, place it back in its hole and then reconnect the spark plug wires to it.

Tips: Simple Steps to Test Which Coil has a Malfunction

  • Start the engine.
  • Keeps the engine running at idle speed.
  • Open the no. 1 ignition coil bolt, and then pull up the coil to see the engine’s condition.

If the engine’s condition becomes changed to rough idling, that means the no.1 ignition coil is good. Then you can continue this step with the next ignition coil until you find the engine condition has no change. When you pull out a faulty ignition coil, the engine condition should not change.