yzhou

2014c63 sedan with 12k miles on it. Check engine light came on today. Have no idea what's wrong with it. The light came on when I drove it to school normally.

Btw I have Renntech ecu on it.



Question is can I keep drive it? The dealership told be to be there on Friday.

abcut973

If you don't have a OBDII reader go to any part store and they will be able to pull the codes for you free of charge.
From there google or post them here and we'll probably able to help you.

Girard@ACGautomotive

Have you touched your airboxes or filters at all?

Thor2j

Call renntech, they're really good about that stuff.

yzhou

not at all

yzhou

Hey guys. Auto Parts pulled the code for me.
They don't have the data for 2014 so we used 2012. I think it's the same?

yzhou

Thank you. They pulled the code out it says misfire based on 2012 c63 data.

yzhou

Bump for help, code p0300 p0302 p0305 p0306 p0307 p0308..

CarHopper

The P0300 is just saying multiple misfires and then the others are saying misfires in cylinder 2/5/6/7/8.

You're using premium gas right?

yzhou

Yes, just bought a full tank of gas form Shell last night.

abcut973

Generally misfires are due to poor ignition or fuel injection. So basically not enough sparks or fuel. I would check the spark plugs to see if there are no black residue on them. That would be your first troubleshoot step. You can try to swap coils to check if they are faulty.
For 12k miles that would be surprising but who knows. You are probably still under warranty so get the car checked/fix by MB.
Driving with misfires is not recommended because long term it could damage your exhaust system. GL

m a x i m u s

did you ask renntech? may be tune related.

yzhou

Thanks, I still need to drive it 100 mile until to the dealership. hopefully it's not kind of “longterm”.

yzhou

Not yet, may be aFter Friday I came back from the dealership.

vastermind

I had a misfire on my previous 2009 at around 23K miles. I remember it was a blinking CEL..Car also started up very rough which scared the **** out of me.

Dealer will change the spark plugs for free under warranty but 100 miles to reach there could be a minor concern.

PkB2014

I just took mine in for this problem. Misfire on 5 and 8.

I have less than 12k miles on the car and had the factory tune on it and the current tank of gas was ethanol free 91 octane. It was still running fine as far as I could tell, but I took it in anyway since this was the first CEL that I've had.

They just cleared the codes and said they reflashed it ('it' being the ECU I assume). Then cranked it up and ran it a few times over a couple days and it never happened again. They gave it back and said it happens sometimes this time of year when the gasoline mixture is changed for the winter. They told me if it happens again I could clear the codes if I want to. I'm guessing it is a problem if it happens regularly.

It has me a little worried and I obviously don't like it happening to car so new (almost 1 year old now though).

CarHopper

^ It isn't something to really worry about. Misfires happen... Sometimes the cause is more serious than others but as long as the car is driving and idling smoothly you'll be fine.

In the past with all my cars, if I got misfire codes and the car was still running fine I'd just clear them and they'd be gone for thousands of miles. Happened always around seasonal changes. Just the car needs to adapt to new parameters.

abcut973

It is kind of odd this happened to you as well. I never heard about the gas change for winter. Good thing it was nothing serious.

yzhou

They replaced all my 8 spark plugs. They can't figure it out why but the spark plugs looks bad. Car runs good now.

diushiyu

hi i got same question about cel on. do you use wechat?