Sula

My 2004 C2 ignition coils are of unknown age, but probably 8+ years old. All evidence suggests they are performing exactly as they should.

Should I think about replacing these proactively? What problems might ensue if I leave them alone so long as they continue to do their job?

Mark I

You'll pick up a misfire. Then you park your car until the new ones arrive. Take a close look at them. Bad ones often look the part, cracked or peeling plastic.

Mbren1979

A long as they keep doing the job, nothing will happen, well except a lot of smiles on your face. The original first design coils were problematic. If your coils were replaced they most likely were updated to the new design. Even if someone replaced them with the original design coil, 8 years is not old for a coil and they should be just fine for a long time. You will develop a misfire if one dies. Just park it until you replace it if that happens. Prolong driving on a misfire can kill catalytic converters. The only other thing you may want to do is relocate the expansion tank drain tube if someone hasn't already. From the factory it is pointed right at a coil. Coils don't take kindly to getting wet.

DBJoe996

Time does not matter with ignition coils, but mileage does. How many miles on your car since the coils were replaced, if ever? The updated ignition coils are bigger and I think provide more bang for the buck. The other thing is the spark plugs...how many miles on your spark plugs? Maybe think about new spark plugs and new coils at the same time.

wyovino

As long as you're not having any issues with them, I would wait until you need spark plugs and then do the coils at the same time. If you start getting misfires in wet weather, then I wouldn't wait.

dan_189

You can tell the version by the type of bolts used to hold them in place.

The newer 997 version have male E-Torx bolts the old version have female hex bolts - if they have the torx bolts probably no need to replace them.

Although if they aren't i'd concur with waiting until spark plugs need to be replaced.

However if you're itching for a DIY project - this is a good one - can't hurt to replace them.

sugarwood

They can go 150k or 200k or 80k miles.
No need to replace.
If you have OCD, then buy one and keep it in the garage.
When you get a misfire, you'll not have to wait 3 days for shipping.
Then again, that's what the dealer is for.
Buy a used one to keep. That's what I did for one of my cars.
Came in handy when I needed it. Same day DIY.