CEL code reading
Thread Starter
Junior Member
Joined: Feb 2025
Posts: 65
Likes: 15
CEL code reading
Hi all,
few days ago I got a CEL (not flashing, barely noticed it) in my GT R and the car was a little weird under partial throttle, power delivery seemed inconsistent. So I restarted the car and the CEL went away, and I've been driving it for the past couple days with no issues and no CEL. I tried to check for code with a cheap amazon code reader (which worked for my other cars) but didn't seem to find any stored codes on the GT R.
I was wondering if I should ask the dealer to check the codes or would my independent shop be able to check that as well (not sure if it would be a Mercedes specific code), or I can just see if it ever comes back?
Has anyone else run into this before? car is stock. Kinda wish there was a way to read codes in the car, my old Viper had that feature
Thanks in advance
few days ago I got a CEL (not flashing, barely noticed it) in my GT R and the car was a little weird under partial throttle, power delivery seemed inconsistent. So I restarted the car and the CEL went away, and I've been driving it for the past couple days with no issues and no CEL. I tried to check for code with a cheap amazon code reader (which worked for my other cars) but didn't seem to find any stored codes on the GT R.
I was wondering if I should ask the dealer to check the codes or would my independent shop be able to check that as well (not sure if it would be a Mercedes specific code), or I can just see if it ever comes back?
Has anyone else run into this before? car is stock. Kinda wish there was a way to read codes in the car, my old Viper had that feature
Thanks in advance
Super Member
Joined: Jul 2014
Posts: 807
Likes: 280
.
Sounds like a potential and transient Misfire, and the ECU has memory and will store Codes.
There is a Service Bulletin on Ignition Coils that have been found to be prone to failure, and should be replaced without cost if they fail
Indy Shop more than likely should be able to reveal the Code.
But for your personal use, one of the best value code readers for MB that i've found and used with great success on '19 GT R, '12 C63, etc etc is Carly:
https://www.mycarly.com/brands/mercedes/
It is extremely thorough and interrogates most if not ALL the systems/sub-systems and should revealed stored Codes.
Nothing for the price ($76 USD) can touch its level of detail.
If Carly or other high-detail level Code Reader still doesn't reveal anything, a trip to the Dealership is reasonable, esp knowing Ignition Coil susceptibility to potential failure.
Let us know how it shakes out!
There is a Service Bulletin on Ignition Coils that have been found to be prone to failure, and should be replaced without cost if they fail
Indy Shop more than likely should be able to reveal the Code.
But for your personal use, one of the best value code readers for MB that i've found and used with great success on '19 GT R, '12 C63, etc etc is Carly:
https://www.mycarly.com/brands/mercedes/
It is extremely thorough and interrogates most if not ALL the systems/sub-systems and should revealed stored Codes.
Nothing for the price ($76 USD) can touch its level of detail.
If Carly or other high-detail level Code Reader still doesn't reveal anything, a trip to the Dealership is reasonable, esp knowing Ignition Coil susceptibility to potential failure.
Let us know how it shakes out!
Thread Starter
Junior Member
Joined: Feb 2025
Posts: 65
Likes: 15
Interesting, thanks for the info! that seems like a recall and my car doesn't seem to be affected, wonder if its a late case (20k+ miles).
I also saw that people had issues with pressure sensors, https://mbworld.org/forums/coupe-roa...code-help.html
Either way I'm heading to dealership in a couple days for routine service so maybe I'll just ask them to scan the code.
I also saw that people had issues with pressure sensors, https://mbworld.org/forums/coupe-roa...code-help.html
Either way I'm heading to dealership in a couple days for routine service so maybe I'll just ask them to scan the code.
Super Member
Joined: Jul 2014
Posts: 807
Likes: 280
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It has not risen to level of Recall, only "Service Bulletin" as noted in pdf below
More pertinent information below, and I believe it was extended to 2019+ MYs, as my colleague with 2019 GT R went in for Ignition Coil replacement after
intermittent Misfires, resolved after replacement of same
https://static.nhtsa.gov/odi/tsbs/20...35511-9999.pdf
More pertinent information below, and I believe it was extended to 2019+ MYs, as my colleague with 2019 GT R went in for Ignition Coil replacement after
intermittent Misfires, resolved after replacement of same
https://static.nhtsa.gov/odi/tsbs/20...35511-9999.pdf
Thread Starter
Junior Member
Joined: Feb 2025
Posts: 65
Likes: 15
I think you are correct, I just switched OBD2 app and found some inactive codes including P0307/P0300 cyl 7 misfire, no date so I can't tell if its exactly the one I saw.
I'll take it to dealer but I wonder if they'll just make me come back if it happens again lol
I'll take it to dealer but I wonder if they'll just make me come back if it happens again lol
Thread Starter
Junior Member
Joined: Feb 2025
Posts: 65
Likes: 15
As I suspected, dealer just said come back if it comes up again. I wonder if I should just get a coil myself and replace it if it comes up while under load at the track or something, doesn't seem too hard
Last edited by leafyamg; Sep 17, 2025 at 01:05 PM.
Thread Starter
Junior Member
Joined: Feb 2025
Posts: 65
Likes: 15
To close the loop here, it misfired again in cyl 7, so took to dealer and they replaced the ignition coil under warranty the same day no questions asked, gave me a nice S class loaner too.
here's hoping that fixes it
here's hoping that fixes it
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Super Member
Joined: Jul 2014
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When you mention it was "covered under warranty" - do you mean you have Extended Warranty on Vehicle, or it was replaced without cost to you, secondary to aforementioned Service Bulletin?
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