Common Ignition Problems

Things not running quite right with your vehicle? Feel like you’re driving on a rough road or using more gas than normal? You might have an ignition problem.

Usually you can identify one of two major issues. If your check engine light is on or flashing, finding the problem is easier. AutoZone’s free FIX FINDER service can help you identify the most likely part causing the issue and make a recommendation for repair.

You might end up needing these

Common Ignition Problems

A side by side comparison of old vs. new spark plugs.

Faulty Ignition Coil, Spark Plug or Spark Plug Wires

An ignition issue can be caused by a faulty or failing ignition coil, spark plug, or spark plug wire set. These critical components of your ignition system keep your engine running smoothly. If they have a problem, you'll notice a rough ride, engine misfires, and possibly decreased gas mileage.

Often times, replacing the failed or failing part will correct this issue.

Ignition coils and wire sets can be replaced with a fairly straightforward job. However, some applications will require removal of major components such as the upper intake plenum manifold. Reference a repair guide for more specific information for your vehicle.

Spark Plugs may require more attention. Some spark plugs need to be gapped and have anti-seize applied before installing and some do not. Check the spark plug manufacturer's requirements. Spark plugs should always be installed with a spark plug socket and tightened to the proper torque. If you need a torque wrench, borrow it from AutoZone through the Loan-A-Tool program.


Oil or coolant contamination

Another common issue is contamination of oil or coolant on the spark plug boot. If the boot is contaminated, the spark plug tube seal, valve cover gasket or components of the cooling system are failing and need to be replaced.

This issue must be addressed immediately as it can lead to failure of the ignition coil, spark plugs or plug wires.

Pinpointing an issue

To help pinpoint an ignition issue or decode a check engine light, stop by your local AutoZone to use our free Fix Finder service to help identify the most likely problem and make recommendations for a repair.


Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

FREE Loan-A-Tool® program requires returnable deposit. Please note that the tool that you receive after placing an online order may be in a used but operable condition due to the nature of the Loan-A-Tool® program.

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