Hi All,

Did my search before posting this, but wasn't able to come up with anything concrete. It seems that perhaps i should start with new o2 sensors (upper), but just wanted some confirmation/insight please.

Car has 10,500 miles on it. 2015 C63 507 Edition. It has ARH Headers with HFCs on it since 4,000 miles.

Summary:
Car was parked for about a month, as i was travelling. Came back, and it fired right up, but started having a very gentle shake when at idle. Took it for a drive, and the longer i drove, the "shake" eventually went away. Still, being the crazy OCD owner that i am, i made an appt with the dealer to have it checked. Do note that this dealership has been very supportive with my car, and never have i had any issues taking it in with the headers. Albeit i never had any engine related issues.

Car went in, and they sent it back, saying there were no issues. Got the car back on 1/21.

On 1/25, i was driving home with my fiance, when the car started shaking, and eventually stalled at the traffic light. I restarted it, and the idle was fluctuating. CEL started flashing.
Pulled over, shut the engine off, locked the doors till car went back to sleep mode, and it started up fine again on the drive home (3 miles).

Plugged my OBD reader in once i got home, to have the following codes:
1. P0300: Random/Multiple Cylinder Misfire Detected
2. P0308: Cylinder 8 Misfire Detected
3. P0306: Cylinder 6 Misfire Detected
4. P0307: Cylinder 7 Misfire Detected
5. P0410: Secondary Air Injection System

Next morning, i was about to get the car towed in, and started it up, everything seemed fine. Took it for a spin around the block, and absolutely no shake from the engine. Called them, and they told me to drive it in.

Now the fun part... This dealership and i have a really good relationship, and everything has been great so far. In fact their level of service made me trade in our Tesla Model X for a GLC 63 AMG.
That said, they called me this morning and said the CEL is due to the ARH exhaust, and that i need the car back to stock before they can diagnose...

Thoughts or suggestions? I know that i have an aftermarket part on the car. But here in MA, there is a law that came out stating that dealerships need to prove a problem is related directly to the aftermarket part, and not just hearsay or speculation.

Thanks everyone.

 

 

I'm betting it's the primary o2' - just had to have mine swapped ( under warranty) as one was intermittent....

E

 

Thanks bud! Hope all is well with the car on your end! BTW, it has become a model for a lot of carbon fiber parts on ebay now