Do Your Ignition Coils Need To Be Replaced Every Time You Swap Spark Plugs?

One of the main differences in regular maintenance between a gasoline and a diesel-powered car is replacing the spark plugs. While diesel engines rely on compression to create ignition, and thus internal combustion, gas engines have spark plugs, which help ignite the air-fuel mixture and cause internal combustion to happen. 

Like the oil and the filters, spark plugs should be changed with regular maintenance, or it could lead to serious problems. Deteriorated spark plugs will prevent the engine from running properly, which could lead to stalling, and it can also have an effect on the fuel economy and make the engine much more difficult to start.

Obviously, the spark plugs do not run on magic, the spark is made possible by the ignition coils. These devices, in simple terms, use electromagnetic induction to step up the 12 volts put out by the car's battery to the thousands of volts needed to generate those sparks. As such an important component, you may think that it requires replacement with every spark plug replacement, but that's not the case at all.

The only time when you should diagnose and replace the ignition coils is when (and if) you notice one of the many symptoms of failing coils. One of the most common symptoms is engine misfires, which you will definitely notice while behind the wheel. As the ignition coil is weak and can't deliver the proper voltage to create spark, the engine will begin to act up and cough.

Another more severe, though perhaps less likely, symptom of a failing ignition coil is backfiring. If the engine notices that the coil or coils can't supply the right voltage, it'll try to compensate by throwing more fuel into the mix. Obviously, this will ruin your fuel economy, but some of that fuel might exit through the exhaust and cause a pop or bang. Not the good kind, unfortunately. If you see a check engine light on the dash, that also might be a warning sign of a failing ignition coil. If you notice one of the other symptoms, break out the code scanner.

Even if your ignition coils aren't showing any signs of failure, generally, these items last between 60,000 and 100,000 miles, due to their prolonged exposure to vibrations, high heat, and constantly needing to transport copious amounts of electricity to the spark plugs. So yes, the ignition coil or coils in your car do need replacements, and they're actually pretty easy to replace as a DIY job.