How to Test Ignition Coils
Here are some tips for testing your ignition coils depending on whether they are CNP (coil-near plug) or COP (coil-on-plug).
CNP Coil Type
1. To test your ignition coils, first turn off your car’s engine and open the hood. Remove or unplug the spark plug wires (if your car uses a CNP coil). These wires usually start at the distributor cap and run to the spark plugs. Wear rubber gloves and insulated tools when working with these electrical components, or you could receive a serious electric shock.
2. Next, attach a new spark plug to the spark plug wire (either a new spark plug or an old spark plug to test the spark in the ignition coil). Using insulated pliers, clamp the spark plug to a metal part of the engine so that the threaded part of the spark plug touches the metal.
3. Remove the fuel pump fuse using a fuse remover or needle nose pliers, disable the fuse and start the engine. You may need another person to turn the ignition key because you will be holding the spark plug with the pliers.
4. After starting the engine, check if there is a blue spark along the spark plug gap. If there is a blue spark, the ignition coil is working properly. If no spark is seen or if orange sparks are produced, this is an indication of a faulty ignition coil.
5. Once testing is complete, remove the spark plug, place it back in the hole, reconnect the spark plug wire, and reinstall the fuel pump fuse.
COP Coil Type
1. Start the engine and allow it to idle.
2. Locate the first ignition coil (they are usually located in the correct order along the engine).
3. With the engine running, carefully disconnect the electrical connector from the first coil.
4. Observe the engine behavior. If this coil is working properly, you should immediately notice a change in the engine’s behavior. It should become more restless or even go out.
5. If there is no change after removing the coil, the coil may already be faulty.
6. Reconnect the coil before moving on to the next coil.
7. Repeat the disconnect process for each coil individually.
8. Please note that removing the coils does not cause any change in engine operation, these could be the culprit.