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Mercedes c207 very strange power and limp mode issue
Hello everyone,I have a strange issue with my Mercedes E350 C207 (2010).I’ve owned the car for about 5 years, and from the very beginning there was a problem with power, but only when I started the engine immediately after turning the ignition on.If I turned the ignition on twice and only then started the engine, the problem did not occur.
For the past month, the issue has been happening randomly, but only after stopping or driving slowly in traffic.It feels like the car goes into limp mode, the gears are held longer, there is a lack of power, and there is a slight jerk when almost coming to a stop. Once it goes into this mode, turning the engine off and on again brings everything back to normal.Also, it does not happen after every stop. Some days the car drives perfectly all day.
I really don’t know what else to do.I have already replaced both EGT sensors, and now the entire EGR valve with a new one.Some time ago I also replaced the intake with MAF sensors because I had faults related to them.I have also cleaned the entire throttle shut-off valve, and it appears to be working correctly.No change.The only fault code I keep getting on Autel, Snap-on, and even the Torque app is:
P0401 EGR Flow Insufficient Detected.
I’m out of ideas at this point. Any suggestions would be greatly appreciated.
Last edited by Damain375; Feb 16, 2026 at 06:24 AM.
Going from your description related to EGR and code...
the internal block passages get plugged up with deposits - Before and passed the EGR valve. wire brush set
Thank you for your answer, so in your eyes what should be next step?
I am almost certain that there is no carbon build up in the intake manifold, because the engine was removed and rebuilt 8 months ago. Unfortunately, the problem seems to have become even more frequent since then.
Thank you for your answer, so in your eyes what should be next step?
I am almost certain that there is no carbon build up in the intake manifold, because the engine was removed and rebuilt 8 months ago. Unfortunately, the problem seems to have become even more frequent since then.
> Cause vs. consequence:
Okay I see, these details are interesting to understand - Then we can consider this report is a misleading us towards the EGR circuit but really is sensor related ??
Have you cleaned the MAP (or MAF) sensor lately?
How do your exhaust sensor read ??
I recently replaced the exhaust gas temperature (EGT) sensor and cleaned out its port.
About a year ago, I also replaced the entire air intake, including sensors, using aftermarket parts(Chinesee?) . I remember I was getting an engine management light with a MAF-related code. Although I was able to clear the error after air intake replacment, the power loss issue remained exactly the same before and after the replacements. Only thing i was able to remove MAF sensor error from ECU.
Somebody mentions swirl flaps motor could be my answer however i thought i would get motor error code but it's nothing apart of
P0111 – Intake Air Temperature Circuit Range/Performance (once) - senor replaced as well P0401 - Exhaust Gas Recirculation Flow Insufficient - Replaced sensor next to EGR and checked/cleaned throttle body - PENDING sometimes CURRENT and sometimes SAVED.
14A600 - high positive control deviation in the Exhaust Gas Recirculation (EGR) system (very rare) - replaced EGR
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