G Wagen Diesel rough starts and MPG issues

Sounds familiar I had similar symptoms last winter Rough starts worse fuel economy until the engine warmed up The error code is almost certainly pointing to the PTC heater which is basically an electric auxiliary heater It kicks in during cold starts to help the engine reach operating temperature faster It's definitely part of your HVAC system contributing to faster cabin heating as well Did you notice if the blower motor was working correctly Sometimes a faulty PTC can affect the blower motor speed

Thanks So are you saying your G Klasse also had a busted PTC heater that caused these exact symptoms When you say PTC heater affecting blower motor speed does that mean the blower motor would not work correctly Did you end up fixing it yourself or going to a workshop

Yep the symptoms were almost identical The PTC heater is supposed to assist the engine warm-up phase and when it fails the engine struggles more especially in cold weather As for the blower motor in my case it was working but some people reported that a faulty PTC heater might affect its performance because it can create an electrical fault in the HVAC system I'd advise against trying to fix it yourself unless you're comfortable with electrical work The PTC heater is integrated into the HVAC system and messing with the electrical system could cause further issues I would suggest you go to a workshop

Right that's the confirmation I needed I'll book it into the workshop and have them replace the PTC heater It saved me a lot of guesswork and potentially making things worse Turns out it was indeed the PTC heater and after replacing it for 350€ the engine is running smoothly again no error codes and the fuel consumption is back to normal So glad I got that sorted