Ignition Coils - Replace one or all?

[Redd]

I'm starting to get misfire codes on coil #7. Trying to decide if I should replace just #7 or all 8 coils.

Has anyone who's replaced only one faulty coil suffered other coil failures shortly after?

[Ervin87]

Just replace the bad coil. No need to replace the other ones.

[sdbmwcoding]

Replace just the bad coil. They're expensive per coil so I wouldn't replace all 8. Have you 100% diagnosed it as a coil? I don't see coils fail often on the s65, majority of the time it's the spark plug

[Redd]

All 8 plugs are less than a year old. Code is consistently thrown by the #7 coil. Plus they're 130k kms old so more than due.

OK will just change the one. Thanks!

[sdbmwcoding]

Originally Posted by Redd

All 8 plugs are less than a year old. Code is consistently thrown by the #7 coil. Plus they're 130k kms old so more than due.

OK will just change the one. Thanks!

Have you tried swapping coil 7 to 8 and seeing if it follows?

[Redd]

Not yet. Will try that.

[Bakerboy]

If one is failing the others will follow soon after and will likely be robbing power.

I tried replacing one but it didn't cure the problem for long.

[bigjae1976]

I'd replace all 8. You'll be back in there replacing another coil. Been there many times...replaced 1, then 2, then 3.

[Bubbles]

Mismatched coils may having you chasing the problem down the road. Resistance differences between the coils may trigger additional codes but you may get lucky with swapping out just one.

Cost benefit and time required to swap should be considered.

[wyatth]

At that age/mileage Id do all 8, but I’m also keen on efficient labor.

[Jive]

I had a single coil fail at 30K miles, diagnosed with codes. Replaced the faulty coil and been trouble free for 8K miles now with no issues from the other coils. It was probably a fluke given the low milage. With you're milage, I would do some research to understand how long coils should typically last.

[M3AN_S65]

I replaced only the one that failed but carry 3 extras with me in case. Especially when I hit the tracks.

[GORDON.M3]

I have no time for downtime. Once you working on it, might as well replace all 8 assuming the mileage is quite up there.

[amrazM]

Originally Posted by sd*********

Have you tried swapping coil 7 to 8 and seeing if it follows?

I would def move 7 to 5, why would you put a bad coil at the back.

[sdbmwcoding]

Originally Posted by amrazM

I would def move 7 to 5, why would you put a bad coil at the back.

True lmao didn't think of that