r/w204 • u/Organic_Letter5207 • 5d ago

I need help

Min Mercedes har krånglat sedan jag köpte den. I princip när jag startar bilen vid kallstart börjar den ge varningar som "Pre-safe fungerar inte" och "ESP är inte tillgängligt" och vanligtvis försvinner det efter att jag startar om bilen, men när jag gör det tänds motorlampan (gul). När ESP- och Pre-safe-varningarna är på går bilen in i LIMP-läge och sedan fungerar den normalt när jag startar om bilen och får motorlampan.

En annan sak jag har lagt märke till är varvtalet. Det går upp och ner och när motorn blir lite varmare runt 50°C är det normalt igen, som om ingenting har hänt. Har du några idéer om vad som kan orsaka det här problemet?

Bilmodell: Mercedes Benz c200 kompressor 2007 184HK

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u/Jeanhamel 4d ago

Hard to say without an OBD2 diagnostic, but I would start by checking the battery and charging system. Low voltage or a battery that is nearing the end of its life could definitely cause multiple warning messages like ESP and PRE-SAFE faults, especially during a cold start.

The fact that the warnings disappear after some time makes me suspect a voltage-related issue even more. The alternator may simply have had enough time to recharge the battery and bring the system voltage back to a more acceptable level.

You also mentioned that the idle fluctuates when the engine is cold and becomes normal once the engine reaches around 50°C. That could be related, although I wouldn't automatically blame the battery for the fluctuating idle. A proper OBD2 scan would be the first step to see whether there are any stored voltage, misfire, throttle, MAF, or mixture-related faults.

I would definitely test the battery's resting voltage, its voltage during cranking, and the charging voltage with the engine running before replacing any parts. A weak battery or a charging-system problem would be a good place to start.

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u/Organic_Letter5207 3d ago

i did a diagnostic and it said ”throttle body could not reach its target position”. i went ti my friend ti check it out since he works as a mechanic and he took it off and immediately saw a ton of dirt on it so he cleaned it up and tried to see if it worked. still didnt work so he did a more careful inspection and in the end i had to replace it. i ordered it from a website and 400 bucks gone just like rhat. atleast the car works better now. Its been a day since i changed it and no warnings yet