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I just had my tires rotated yesterday and on the way home I noticed that my 2015 C300 had rough idle every time I would stop for a red light. It idles at about 7000 RPM. There is no check engine light and no codes came up when I ran a full scan with my Autel MaxiCheck. The car only has 25k miles and is out of warranty but I am up to date with maintenance. I haven't been able to find any posts regarding my situation. Anyone have any suggestions? I would really appreciate the help.
I revved the engine while I had my foot on the brake and the engine barely moved so I guess it's not the engine mounts. My indy mechanic wants $105 to diagnose the rough idle but I am hoping that this is something that I can fix myself. Not sure what to look at next since my scanner didn't find anything. My scanner does have the live data feature but not sure how to analyze the information.
I ran another scan today and it is now showing fault code P13C523. Still no check engine light and it still has intermittent rough idle. I searched the internet and forums but couldn't find anything for this code. Is there anyone that can please help?
I’ve been feeling something similar with no check engine light. Feels like an abrupt jerk or shudder happens at idle, only happens intermittently but you really feel like something might be wrong. 2015 C300 51k miles. Not sure if I should go out of my way and diagnose it with a mechanic.
I experienced a similar situation with my 15 C300. Currently has 51k miles. Out of manufacturer warranty as of 2 months and 1k miles but have an extended warranty. Took into local Mercedes dealer for diagnosis and they said it needs the pistons replaced as it had the infamous wrist pin issue. Currently has been there for over 2 weeks and we are still waiting on approval from our extended warranty as they are sending our their investigator. Hopefully that isn’t your case but just wanted to share my experience
I experienced a similar situation with my 15 C300. Currently has 51k miles. Out of manufacturer warranty as of 2 months and 1k miles but have an extended warranty. Took into local Mercedes dealer for diagnosis and they said it needs the pistons replaced as it had the infamous wrist pin issue. Currently has been there for over 2 weeks and we are still waiting on approval from our extended warranty as they are sending our their investigator. Hopefully that isn’t your case but just wanted to share my experience
I doubt that in my case it’s the wrist pin repair. I had the wrist pin repair which took 3 weeks when my car was at 41k miles. I recently had my car serviced with engine oil, engine air filter, spark plugs, transmission fluid and filter, and brake fluid exchange which makes me think it could be something related to any of those but not exactly sure.
I doubt that in my case it’s the wrist pin repair. I had the wrist pin repair which took 3 weeks when my car was at 41k miles. I recently had my car serviced with engine oil, engine air filter, spark plugs, transmission fluid and filter, and brake fluid exchange which makes me think it could be something related to any of those but not exactly sure.
I would look at either spark plugs or a vacuum leak
I doubt that in my case it’s the wrist pin repair. I had the wrist pin repair which took 3 weeks when my car was at 41k miles. I recently had my car serviced with engine oil, engine air filter, spark plugs, transmission fluid and filter, and brake fluid exchange which makes me think it could be something related to any of those but not exactly sure.
P13c523 A short-term torque limitaion was detected by the knock control no signal change voltage level is too low
check and make sure all the spark plug boots are connected correctly, coil packs are all correct. This code can be triggered by bad/lose spark plug connetion
I doubt that in my case it’s the wrist pin repair. I had the wrist pin repair which took 3 weeks when my car was at 41k miles. I recently had my car serviced with engine oil, engine air filter, spark plugs, transmission fluid and filter, and brake fluid exchange which makes me think it could be something related to any of those but not exactly sure.
Wow 3 weeks. Hoping to have it back next week. Did they rebuild your engine for the wrist pin repair? My extended warranty is trying to get a used motor that is not in the “issue vin numbers” but the service tech is trying to push for a rebuild. Definitely sounds like your issue is related to your recent service.
Yes I checked the spark plug connectors and coils and everything seemed to be fine. Then today I drove it for a couple of miles away from the house. Almost immediately, I noticed that it was running very rough and felt like it was going to stall out while driving or stopping at an intersection. I was going about 45 mph when the car started shaking violently. The check engine light came on at this time. This is the first time I've ever seen the CEL since I bought the car in February. I quickly pulled over at this gas station and turned off the ignition. I restarted the car about a minute later and the check engine light didn't come on but it still had rough idle whenever I stopped. It seemed to run fine on the way home. As soon as I got home, I ran another scan and it now has 2 more fault codes: P030085 and P030185.
So it looks like cylinder 1 is misfiring. I removed the cylinder 1 coil pack and of course I broke the little plastic gray tab that you have to push out before you can disconnect the electrical connector. I found the pic below online but I still managed to break the plastic tab. I was going to remove the spark plug but then I realized that the spark plug socket that I use for my 2005 ML500 was too big. I checked online and I think the correct size for the 2015 C300 is a thin walled 14mm socket. Since I couldn't check the spark plug at this time, I decided to switch the coil packs between cylinder 1 and 2. I am thinking that if it throws another code for cylinder 1, it's the spark plug. And if it throws a code for cylinder 2, which I put the coil on from cylinder 1, then it's the coil. A new coil pack from my local dealership cost $157.61 but I can order one online from FCP Euro for $85.86.
After switching the coil packs, I drove around for about 30 minutes but it didn't throw any new codes. Check engine light didn't come on and no new codes when I scanned it. On Monday, I'll be taking a 40 mile round trip for an appointment so maybe I'll know more then. I'm also planning to get the correct spark plug socket so that I can check the plug.
Gray plastic tab on electrical connector to disconnect coil pack
Last edited by lvbatteryguy; 10-12-2019 at 08:23 PM.
I finally got the 14 mm spark plug socket that I ordered online. I removed the spark plug from cylinder 1 and it looked pretty dirty. On the way to the auto parts store to get a replacement, the check engine light came on again. I scanned it when I got home and the P030185 code came up again. I put the new plug in and drove about 40 miles today. The rough idle was no longer there, shifts were really smooth, and it accelerated very strong. I've only had this car for 8 months and it's never felt like this before. It would always hesitate whenever I floored it and I thought it was just turbo lag. Now it responds almost instantly and there is no rough shifting or hesitation like before. I'm thinking that this spark plug problem already existed when I first got the car and it just got worse over time. I'm going to change the other 3 plugs asap. The spark plug cost a total of $15.14 at my local auto parts store but I can get them much cheaper online.
I still have the P13C523 code (A short-term torque limitation was detected by the knock control. No signal change: Voltage level is too low.). I not sure exactly what is causing this code and I haven't been able to find anything by searching online or the forums. The car is not a daily driver but I do use premium fuel: Shell V-Power NiTRO+.
One thing I noticed with the spark plugs. The original plug is NGK Laser Iridium SKU#: SILZKFR8C7S with the Mercedes logo on it. The new plug is also NGK Laser Iridium SKU#: SILZKFR8E7S but with the NGK logo. They looked virtually identical with the same gap of .028. I guess the new spark plugs with the E instead of C is an alternate SKU# with the only difference is the logos.
Last edited by lvbatteryguy; 10-14-2019 at 08:21 PM.
starting to experience a slight rough idle on my C300 (70k miles).
i changed the spark plugs 20k miles ago but one could have gone bad. will see what happens if it gets worse! thanks for posting all your updates, was very helpful!
I ran another scan today and it is now showing fault code P13C523. Still no check engine light and it still has intermittent rough idle. I searched the internet and forums but couldn't find anything for this code. Is there anyone that can please help?
Hi lvbatteryguy,
Did you manage to fix or clear the P13C523 code? I'm in the same boat now and got this code, but I'm not sure what caused it. I did a few things:
Replaced the main battery with a Costco Interstate battery, which is a little smaller than the original.
I pulled the spark plugs (which are 20K miles old) just to examine the cylinders with a borescope. they look good to me, some rust (big question where it came from). Asked in this post to help me evaluate them.
A week later, which was yesterday, I scanned the car and found the same code as yours stored in N3/10 - Motor electronics 'MED40' for combustion engine 'M274' (ME) control.
Frequency counter shows 1 and Number of ignition cycles since the last occurrence of the fault = 37.
This makes me believe that I drove the car 37 times without the knock control registering any more issues. Did I get this right?
I can't clear this code with Xentry or ThinkCar. I'm not sure how to clear it. There's no CEL or other messages, and I haven't noticed any differences in the engine's sound, performance, or anything else.
09-11-2019, 10:52 PM
