Coil life

how long should the coils life span usually run?

I have a 1999 I-30 infiniti and I am have a 2nd one replaced. Currently the car has almost 76,000 miles.


Your six cylinder engine has SIX ignition coils … one on top of each spark plug. One failing is not surprising. Two failing …Wait! Is the car under warranty? At $75 each (at Advance auto parts), that can become expensive after a while. If it’s out of warranty, and you don’t have full faith in the shop now doing your car repairs, you should check around for a quality shop. There comes a point where I question the troubleshooting skills of some mechanics.

No , not under warranty - car is going on 9 years old.
I do have faith in this shop, which specializes in foreign makes and is a neighborhood 20 year staple.

When the 1st coil malfuctioned the 1st shop (3 years ago) I had been going to could not diagnose it,even using the computor which I do not think the one they had was very good. Eventually I brought it to this shop and like the business as a whole. Just wanted to know normally, what life expectency should the coils have

So, have the spark plugs every been replaced?
Most coil failures are due to a chronic engine miss; even subtle ones caused by plugs or any other part of the engine management system.

The coils today aren’t the biggest things made. Even the monsters of yesteryear didn’t hold up forever. Collectively, ignition coils are going to fail due to the huge numbers made today. When every four cylinder car has four instead of one; you have four times the odds of one failing before 100,000 miles. Beats the heck out of the old Ford spark plug wires with 100% chance of failure in 20,000 miles due to heat.

O.K then - my car has 6 , this is the second one to be replaced.
the spark plugs were replaced 1 1/2 years ago and were checked as well when
ignition coil showed bad on computor read out. The plugs looked fine.

I hate to ask, however I would like to keep my car for at least another 25 -30,000 miles becuz it is in such good condition. Am I looking at the other 4 to be replaced before then? Yish . OK4450 says chronic engine miss, what else could be causing that if the the plugs are good?

These “coil packs”, where each spark plug has its own coil, were supposed to be a big improvement over the older single coil system because they eliminate the distributer and plug wires. In the real world, these new, very compact coils have had more than their share of failure problems. I own a Crown Vic which uses this system and have had 3 out of 8 “coil packs” fail, at $100 a pop, retail. I bought some spares on eBay and now carry them in the trunk to avoid being stranded out on the road…I have also learned (the hard way) that washing these engines is the kiss of death for coil packs…

Caddyman is exactly right about moisture being the kiss of death. On engines with the spark plugs in the bottom of a well, condensation or pooled water has nowhere to go. It then corrodes the connector that attaches to the spark plug.
This corrosion then forces the coil to work harder and can lead to a short life.

You also see this on vehicles that do not use the COP (coil on plug) arrangment. It also occurs on vehicles that use regular spark plug wires with an extended tip for reaching down into that well.
This moisture problem does not occur near as frequently on engines that use totally exposed plug wires.

I had to go in a while back on my 4.6 Lincoln for something similar to this. It had developed a very, very subtle engine miss and the front 2 plug wires on one side had corrosion on the ends due to moisture seeping in around the plug wire boots. Nothing a little cleaning and electrolytic grease would not fix.

For what it’s worth, I’m a fan of systems that use one coil although those are disappearing fast.

Well I have learned alot. I am in Florida, lots of moisture and rain too.
How can I keep the other coils-plugs from a short life. Do I have my mechanic clean this area next time I have service. Or is it – it is what it is? Can I do any periodic maintance too?

My opinion is that spark plugs should be changed every 40-50k miles at the most. Others have different opinions.

When the plugs are changed it is the duty IMHO of the mechanic to also inspect the plug wire or boot ends for damage or corrosion.
It is a simple matter of cleaning them with what is called a “distributor tower” brush. Following cleaning, they should be lubed with electrolytic grease.

JMHO, but I think this is a step that should be thrown with the plug replacement charge and the customer should not be billed for it. Five or ten bucks extra, maybe, if the shop feels they must charge something.
JMHO for what it’s worth.

Your odds are good either way. You may never have a different one go out. The new ones have the same odds as the old ones, and they can be cracked when the plugs are changed. They’re good plastic, but they’re still plastic. Fix it and drive it but don’t worry about it.

Just got back to see your reply - what is OMHO and JMHO (stand for)


IMHO is in my humble opinion. Similarly JMHO is just my humble opinion.

Got it - very good - thanks for everyones imput and help