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Purpose:
To discuss the common symptoms of Ignition Coil Failures.
Introduction
What is an Ignition Coil? An ignition coil is a component of an automobile's ignition system and is responsible for providing the high voltage for the spark plugs to ignite the fuel. An induction coil consists of an iron core and two insulated coils: an inner primary coil has relatively few turns of copper wire, and the surrounding secondary coil has many turns, about 100 times more than the primary coil.
There are some symptoms to determine whether your ignition coil(s) faulted. These are:
- Check Engine Light On/ DTC Codes
- Misfiring or Stalling
- Rough Idle
- Car Won’t Start or Rough Start
- Poor Fuel Economy
1. Check Engine Light On/ DTC Codes

If you are driving with an ignition coil problem, the check engine will illuminate and set a P030X misfire code where 'X' is the number of the misfiring cylinder. In addition, you can check for ignition coil problems with an OBD II scanner.
2. Misfiring or Stalling

There could be a problem with the ignition coil if the engine misfires or stalls at idle, stop suddenly, or accelerates. The misfire results from the engine’s cylinders not firing correctly or doesn’t work at all. They sound like a coughing or sputtering noise or feeling like a jerk or strong vibration.
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3. Rough idle

When the vehicle is idling, you will feel the engine is fluttery or inconsistent idle. When stepping on the accelerator to increase speed, you also feel the vehicle hesitate and jerk forward.
4. Car Won’t Start or Rough Start

The ignition needs to spark at just the right time for the engine to start and a vehicle to run. If the engine has several bad ignition coils, you will find it hard to start the engine.
5. Poor Fuel Economy

Less power providing the spark plug causes vehicles to expend more fuel to compensate for insufficient power. If you notice that the car expends more fuel when you drive the same distance, it’s a sign of a bad ignition coil.
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