dmronan

Hi all, 2014 C63 here, 65k miles, sparkplugs were replaced roughly 8k miles and about a year ago. Never replaced ignition coils.

I was out on a drive this past Sunday, car is running completely fine. I hit a speed bump at a decent speed - CEL immediately comes on. Car is still running fine so I make it back home with no issue.

I throw on the code reader, I get code “P0355”.
“Ignition Coil “E” Primary/Secondary Circuit.” It indicates that the powertrain control module (PCM) detected a problem in either the primary (computer side) or the secondary (spark plug side) #5 ignition coil “E” circuit.”

I pop the hood and first thing I notice is the right air filter housing is loose. After inspection, I see the clip on the bottom of the housing that mounts to the engine is bent. I bend it back into place, but it doesn’t fully clip on as the other housing does that has a non-bent clip. I read online and people have said this code has been triggered just by this housing not being fully connected to the engine

After getting it on as tight as I can, I start it back up and bring for a quick drive to see if code will clear. No luck but the car runs, sounds and accelerates completely normally.

This is a long story, but has anyone had any experience with this code? chances are that it is triggered by just the loose housing/defective clip given the context?

Nathan Grimmer

I'd say to start with the coils, maybe cylinder five