paulakaiser1
Mercedes GLK diesel performance issues resolved
Summary of the thread
A 2011 Mercedes GLK diesel experienced performance issues, including stalling, increased fuel consumption, and smoke during acceleration, with the check engine light on. Initial checks pointed to a faulty mass air flow meter, which can disrupt the air-fuel ratio and cause such symptoms. After replacing the mass air flow meter, the vehicle's performance improved, resolving the stalling, fuel consumption, and acceleration issues.
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4 comment(s)
paulakaiser1 (community.author)
Yes, there's a slight delay in throttle response, especially when overtaking at higher speeds. Does this make a mass air flow sensor failure more likely, or could other things be causing the performance drop?
ameliemoon18
That hesitation could be the mass air flow sensor struggling to read properly. I can't be certain, but with those symptoms, it's likely. I'd suggest a good workshop for a proper diagnosis. Better to be sure than guess.
paulakaiser1 (community.author)
The workshop visit confirmed the mass air flow meter was faulty. The replacement was 365€. Now the engine runs smoothly, fuel economy is back to normal, and acceleration is responsive. Thanks again for the advice.
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GLK
ameliemoon18
I also have a GLK, though a different year. Your symptoms sound familiar. Higher fuel use and stalling might mean a mass air flow problem. Do you notice any hesitation when accelerating, besides the smoke? A bad mass air flow sensor can mess up the air-fuel ratio. But, I'm not sure it would cause all those problems at once.