Hi to all, I’m new to the forum because I’m trying to help my father in law who has owned his 1999 c 240 from new which has always been looked after and is in immaculate condition. Problem is that the other week he tried to start the car and it wouldn’t fire up, local garage identified the external pump as the issue and replaced it, a day later it wouldn’t start again so they replaced the new pump again, next day same problem. They have had the car back and diagnostic tells them that the ECU is faulty and should be changed. Merc want over 1k to do this work but have told the old man that if the fault persists he can’t get his money back but they will charge him more to find the further fault. I’ve heard that you can swap over the ECU along with associated parts but not sure what is needed or how it’s done. My thinking is that it’s cheaper to swap the ECU with a second hand unit for a few hundred and if that rectifies the issue then he’s good to go. Also could it be a persistent wireing break or relay. I’m not sure as I’m not familiar with Merc but I’m handy in the engine bay. Please let me have your thoughts on this as it would be a shame to see this car on the scrap heap.