Why is my Car Ignition Coil getting Hot/Melting?

Why is my car ignition coil getting hot?

Your car’s ignition coil may be getting hot because of excessive current flowing through it. This happens when the resistance in the spark plugs and wires is much lower than what is expected.

As a result, there is voltage/current overload on the ignition coil and it starts getting hot.

You can avoid this by checking the damage in the spark plugs or wires that may be causing the value of resistance to fall below the expected value.


How hot should an ignition coil get?

The ignition coil of your car may heat up to a temperature range of 200 degrees Celsius or 392 degrees Fahrenheit when the engine has just been turned OFF. It’s recommended that you don’t touch the ignition coil immediately after the engine has been turned OFF.


How long should the ignition coil last?

The ignition coil of your car must last for at least 100,000 miles or 160,934 kilometers if the coil hasn’t undergone any damage or failure.

However, the lifespan of the ignition coil may vary depending upon the condition of the spark plugs and the resistance in the wires.


Car Ignition Coil getting hot


Hot ignition coil symptoms

A hot ignition coil can be identified by symptoms like a hard-to-start engine, flashing check engine light, jerks in the engine and low power, stalling car, misfiring engine, poor fuel efficiency and backfiring car.

  • Hard to start the engine
  • Check engine light flashing
  • Engine jerking and less power
  • Car stalling
  • Engine misfiring
  • The poor economy of fuel
  • Car backfiring


Hard to start the engine

A hard-to-start engine is an important symptom of an ignition coil getting hot. This happens because the spark plugs are unable to start the engine due to a faulty ignition coil.


Check engine light flashing

If your car’s ignition coil is getting too hot, the check engine light on your car’s dashboard will begin to flash. The code can be scanned using an OBD scanner.


Engine jerking and less power

Lack of power and engine jerking while stepping on the accelerator are a couple of frequently observed symptoms of a hot ignition coil.


Car stalling

This happens when the spark plugs receive intermittent sparks from the ignition coil because it’s hot. As a result, the engine stops and may not even restart.


Engine misfiring

Engine misfiring refers to a rough noise that mimics a coughing sound coming from your car engine when you try to start it. This happens when the ignition coil has become bad because of overheating over a period of time.


Poor economy of fuel

When your car isn’t giving the expected mileage, it’s because of a bad ignition coil. Poor fuel economy is one of the most noticeable symptoms of a hot ignition coil.


Car backfiring

If you see black smoke leaving the exhaust pipe of your car, it’s probably due to a hot ignition coil. This happens when the fuel in the combustion chambers doesn’t burn properly. If this is not set right, it may lead to heavy repair costs and coil failure.


Hot ignition coil problems

A hot ignition coil may result in problems like car engine misfiring, hard acceleration, poor engine efficiency, and so on.

Here are some common problems due to a hot ignition coil:

  • Engine misfiring
  • Jerking while accelerating
  • Poor fuel efficiency
  • Unburnt fuel in the combustion chamber
  • Check engine light ON
  • Engine unable to start


Why does the car ignition coil get hot when the key is in the ON position?

The car’s ignition coil gets hot when the key is in the ON position because the windings of the coil are constantly charging and discharging in this key position to start the plugs.

When the key is not turning away from the ON position, there is a constant high current in the coil because the resistance is very low. This generates heat and the coil gets hot.


You can fix this issue by:

  1. Start the car quickly without leaving the key in the ON position for not more than 3 seconds.
  2. If you want to get power in the electrical accessories of the car, it is recommended to turn the key to ACC position rather than keeping it in ON position. This won’t heat the ignition coil and doesn’t drain the battery too.


How to stop a car ignition coil from overheating?

You can stop the ignition coil of your car from overheating by not leaving the car key in the ON position, controlling the engine temperature, checking the spark plugs, and so on.

  1. Never leave the car key in the ON position for more than three seconds.
  2. Check the spark plugs to find any faults in them. A faulty spark plug is unable to transfer the spark from the coil to the engine and hence, the coil gets overheated.
  3. Inspect the spark plug wirings to see if they are brittle. Brittle wiring may create electric arcs in the windings of the coil that leads to the overheating of the ignition coil.
  4. Look for carbon deposits on the spark plugs. Remove the carbon or corrosion deposits and other debris from the spark plugs.
  5. Bad spark plug ignition cables produce high resistance that causes overheating of the ignition coil. Replace damaged spark plug ignition cables to stop the ignition coil from overheating.


What causes an ignition coil to melt?

The ignition coil may melt because of shorting of wires inside its plastic casing or the engine running at very high temperatures. The aging of the insulating material of the coil can also cause the ignition coil to melt.

  • Shorting of the wires
  • High engine temperature
  • Aging of the insulating material


How to remove the melted ignition coil from the car?

You can remove the melted ignition coil from the car by locating the melted coil and using a lubricant to remove it. To do this, you will need the following tools.

  • Screwdrivers
  • Owner’s manual
  • Lubricant


Here is a step-by-step procedure to remove melted ignition coils from your car:

  1. Disconnect the battery of the car by removing its negative terminals. It’s advisable to do this whenever you are dealing with any electrical components of your car to prevent shocks.
  2. Locate the ignition coils in your car with the help of the owner’s manual. They are usually located on top of the car engine and under the hood of the car.
  3. Using the screwdrivers, disconnect the screws, bolts and electrical connectors from the ignition coil.
  4. Once the screws and connectors holding the coil in place are disconnected, apply some lubricant on the coil and leave it on for some time. This will allow the melted coil to leave the surface on which it was resting.
  5. Remove the ignition coil from the car and replace it with a new one. To install the new ignition coil, connect the electrical connectors and screws in the reverse order of removing them. Don’t tighten the screws and bolts too much as this can make the replacements difficult. Tighten them just enough so that the vibrations in the engine don’t cause the bolts to loosen and fall off.
  6. When the ignition coil is installed and the connections are secured, connect the negative terminal of the car’s battery and test the new coil.


Car ignition coil getting hot and no spark

If the car ignition coil is getting hot but there is no spark, it’s because of misfiring cylinders, a bad spark plug, faulty spark wires or a broken distributor cap.


Tools needed:

  • Scan tool
  • Dielectric grease
  • Wrench
  • Ohmmeter


Here are some steps to fix each of these issues:

  1. Using a scanning tool, locate the misfiring cylinders in your car by reading the diagnostic trouble codes. Identify the cylinders in your car that are not firing and get them repaired or replaced by a professional mechanic.
  2. Turn the car engine OFF and locate the spark plugs in the hood of your car. Follow the spark wires to locate the coil pack to spot any burnout. Screen the spark plugs to see if the spark is traveling to the ground.If the spark is reaching the ground from the spark plug, use a wrench to replace the spark plug with a new one by applying dielectric grease.
  3. To check the spark plug wires, remove them and check for any cuts in the wires. Look for carbon deposits on the plug. Connect the wires to the plug and turn the car ON. With the help of an insulated tool, lift the wires away from the plug. Ground the insulated screwdrivers using jumper cables.Now slowly run the screwdriver along the length of each wire to check for any electric arcs or snapping sounds. An electric arc coming from the wire to the screwdriver is a sign of a faulty wire.
  4. A distributor cap supplies the electric current to the cylinders at a fixed time. To fix the no spark, ignition coil getting hot condition of your car, locate the distributor cap. Carefully observe the outside of the cap to spot any cracks and/or loose-fitting or broken spark plug wires. Mark the location of the distributor cap using a red marker. Remove the cap to inspect its inside.
  5. Before inspecting the inside of the cap, look for black powder at the bottom of the rotor. The black powder indicates the burnout of the electrode.If there is no powder here, check for condensation inside the distributor cap. Condensation can be caused by no spark condition. Replace the distributor cap and the rotor if you spot condensation inside the cap.

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