The ignition coil is one of the core components in the ignition system of a car, also known as the high voltage package. Its role is to provide high-voltage electricity to the spark plugs and to give the cylinders a non-stop ignition. If there is a problem with the ignition coil, it will cause the engine to shake at idle, gasping for air and missing cylinders. There will be a noticeable shaking of the body during driving, weak acceleration and increased fuel consumption.

Nowadays, EFI models usually have one ignition coil for one cylinder, but there are also two ignition coils for one cylinder. If there is a problem with the ignition coil, it will cause a cylinder to be misfiring, which means that the spark plugs will not fire and the gas mixture in the combustion chamber will not burn, and the cylinder will not work. A four-cylinder engine, for example, becomes a three-cylinder engine, and power is definitely reduced. And a missing cylinder will make the engine run out of balance and shake. When the vehicle has this fault, you can conclude that the ignition coil may be faulty.

How to check and troubleshoot ignition coil failure? There are three specific ways.
First of all, you can read the fault code through the computer detector, plugged into the OBD interface, if it shows that there is an intermittent misfire fault in a cylinder, you can generally determine that the cylinder's ignition coil is faulty and needs to be replaced.
Secondly, when the engine is idling, pull out the ignition coils one by one, pull out a little distance and listen for a snapping sound, if the snapping sound is weak or not, it means that the ignition coil of the cylinder has a problem. This can be done by swapping the ignition coils with each other.

Finally, the ignition coil can be checked by using a multimeter. For example, the four-wire ignition coil is the power wire, ignition feedback wire, ignition signal wire and earth wire. The voltage of the feedback signal line of the ignition coil can be detected by a multimeter. In the state of the car, the normal voltage of the signal feedback line is about 5 volts, if it is lower than 5 volts, it means that the ignition coil is damaged internally.