4pfmalachi

Just replaced my engine in a 2013 c250 and after i replaced it the mechanic told me the high pressure pump was broken so we replaced the High pressure pump and after he said he drove my car and it was fine but i get it and i drive a half a mile and it was driving like it was in limp mode but it realistically not and i pulled over now it won’t crank but it turns and tries to start ? what could it be