Should You Replace Your Ignition Coils When You Replace Spark Plugs?
You're hunched over the engine with your wrist painfully contorted, wishing you were Mr. Fantastic. You've finally removed broken spark plug number four and then the intrusive thought hits. "Should I replace the ignition coils too?" The urge is tempting; since you are in that situation, you can strike two birds with one stone. But should you?
To understand the argument, you've got to know how these parts work together. The spark plug creates the spark, obviously. But the ignition coil is the little transformer that takes your battery's mild 12 volts and ramps it up to something aggressive enough to fire a combustion mixture. They're teammates, and when one slacks off, the other suffers.
Many mechanics insist that coils should not be replaced unless they're actually failing. Coils don't wear down the same way spark plugs do, so you should look out for their own warning signs. The symptoms are usually obvious: misfires, a rough idle, sluggish acceleration, or fuel consumption so bad your wallet starts filing complaints.
Some shops recommend replacing both at the same time since their lifespans tend to overlap. Coils commonly fail around the 100,000-mile range. Of all the different types of spark plugs, iridium plugs have the closest comparable lifespan. If you're using weaker plugs that are overdue for a replacement, the extra strain they place on your car can also shorten coil life. Weak plugs can cause a coil to overwork and eventually break down.
Ignition coils and spark plugs need to be changed on a regular basis. Not as frequent as the ludicrous 3,000-mile oil change rule, but a lot of owners forget this practice.
Sometimes you get frustrated in guessing which part is busted and think, "Why not change all of it?" Coils work as a group, so it is ideal to replace all of them at once. If one coil is rotten, others could be too. Changing piece by piece is okay if you're on a budget or if you're experienced enough to pinpoint which is the problematic one. Some owners think it's just an added expense and impractical to throw away non-defective coils. But it's really up to you.
Another reason to replace everything at once is accessibility. Some engines bury ignition coils under intake manifolds or plastic jungle gyms, with those poor designs making your task much more challenging. If you're not all that flexible, doing coils and plugs together can just make sense. Bring your ride to your trusted repair shop if you don't have the diagnostic tools or testers; they'll know how to handle it. Just ready that debit card, credit card, or Cash App because you're going to be spending a lot. And whatever you do, skip the no-name bargain coils that might not even last a few weeks. Don't give yourself another problem.
