Same coil pack keeps going bad

I have a 2006 Grand Prix and the same coil pack has gone 3 times in one year. Each time i have my coil pack replaced i also get my spark plug replaced. Why does the same coil pack keep going bad and how can i fix it?

Is any part of the coil or plug getting wet somehow?

The problem might be caused by a faulty ignition control module that the coil packs plug into.

The ICM functions in two modes. These are the start and run modes.

During the start mode, the ICM allows full battery voltage to the coils because the battery is being drawn down from using the starter, and the engine might be cold from sitting.

Once the engine starts, and ICM switches to the run mode, it’s suppose to drop the voltage to the coils because the charging system comes on line.

And if an ignition coil see’s 14-15 volts instead 8-10 volts, it’s not going to last very long.


I suspect this would burn up all the coils, not just one…?

I’m guessing @Tester is probably spot on. But I’ll chime in with an alternate theory. Too wide of spark plug gap can damage a coil pack. Is it possible this cylinder’s SP gap is wider than the others? Just b/c a new spark plug is installed doesn’t imply the gap is correct. Suggest to remove some spark plugs and compare their gaps to the new spark plug. All the plugs including the new one are exactly the same part number, right? If not, that could also contribute to this problem.

Admittedly reaching on this next one, but if the spark on that cylinder is jumping someplace it shouldn’t before reaching the spark plug, that could damage the coil too. So carefully check the spark plug wires for connectivity (the ohm measurement should be similar to adjacent wires) and signs of insulation cracking. If you have the original high voltage wires, might be worthwhile to replace them.

I assume your car has the 3.8. You state the coil pack is continually failing and use the term spark plug in the singular so that could lead to additional questions.

Is the car running rough or does it just quit when the coil acts up?
If the former, is it the same cylinder each time?
By “spark plug” do you mean one plug or the entire set?

Any DTCs set and who has been doing the diagnosis?

Any chance the coil may not be the problem and running fine after a new coil is installed is purely coincidental?

Pardon the questions but there’s some gray area here.