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      05-27-2013, 11:57 AM   #1
New Member

Drives: 08 E90 M3 6spd Jerez Blk
Join Date: Apr 2013
Location: Denver, CO

iTrader: (0)

Ignition Coil Replacement

I was accelerating up an on-ramp on I-95 on my way home from work the other day and my baby went into "limp mode", check engine light yellow, yellow "engine" graphic, increased emissions warning, decreased max RPMs/output.

Being a very DIY kind of guy, I searched the forums and discussed with other owners and thought it might be a bad O2 sensor. However, I knew that I wouldn't know for sure unless I read the error codes the car was throwing.

BTW, the CC-ID code was 31. A list of codes that you can find without a reader is found here, but only told me what I already knew.

Well, I didn't have a OBD-II reader and I didn't wan't to drive my baby with a potentially damaging error, so I took it to the dealership. They charged me $85 to determine that it was a failed ignition coil on #6 cylinder and quoted me $450 to replace it.

I read somewhere that O2 sensors and ignition coils start going bad around 50,000 miles. Can anyone confirm that they have had the same experience?

Determined to replace them as they fail, but not to be charged $85 every time I need to find out which one went bad, I bought this cable and installed INPA.

A list of INPA error codes is found here.

The Ignition Coil Part Number is 12137841754.
Mine was $56 from

The error codes for a bad ignition coil are (if any ONE of these is thrown you have a bad ignition coil at that cylinder):

Misfire with shutdown cylinder 1
Error will cause a warning light

Misfire with shutdown cylinder 2
Error will cause a warning light

Misfire with shutdown cylinder 3
Error will cause a warning light

Misfire with shutdown cylinder 4
Error will cause a warning light

Misfire with shutdown cylinder 5
Error will cause a warning light

Misfire with shutdown cylinder 6
Error will cause a warning light

Misfire with shutdown cylinder 7
Error will cause a warning light

Misfire with shutdown cylinder 8
Error will cause a warning light

Cylinder numbering is 1 through 4 on passenger (right) side and 5 through 8 on driver (left) side. numbers 1 and 5 are at the front, 4 and 8 are at the rear.

Ignition firing order is 1-5-4-8-7-2-6-3).

Bank-1 is the passenger side (cylinders 1 through 4), bank-2 is the driver side (cylinders 5 through 8).

Removing and replacing the coil pack is straightforward and part of the spark plug replacement DIY found here

Last edited by jfirwin; 05-27-2013 at 12:31 PM.