Hi guys,
Bought a 2017 Mercedes E350e plug-in 5 months ago. Since then, I was 3 times in 2 Mercedes garages because the Engine Management Light (EML) comes ON quite often. First time I saw it on, I've read some info to try and switch it off myself. I found that if I fill the tank with petrol and do some ignition ON/OFF it should dissapear. And it worked but not immediately. It went off after driving about 50km. When it came ON second time, I thought I'd better go to the garage to find the problem. When conecting the OBD they found that there is misfire in Cilinder 4. After 4 hours of diagnostics (swaping the injectors, coils and spark plugs) they said the problem was in the spark plugs. So they replaced them. I took the car and drove 2 weeks and the EML came ON again. Went to them second time, and they said that after swaping coil cables the fault went off so maybe that was the problem. They told me to drive, and if it will come ON again, come and we will replace the coil or injector from cilinder 4. I drove again 2 weeks, and again, IT'S ON. At that point, I didn't want to go to the same garage again. I thought they are just incompetent. So I brought it to a different Mercedes garage and explained everything that was found and done so far. Now these guys kept my car for a week. They said they removed and swapped again the injectors, put them back with new washers, bla bla bla. INJECTORS ARE GOOD!!! So, these guys now say that probably the coding for the injectors was bad, and that they've coded them, and now the car should fly. Gave me the car and told to drive, and if the light will come ON again, come back to replace the injector conectors or the ECU. That was last week. Now the light is ON again. Regardless of the EML being ON or OFF, everytime I start the engine it doesn't run smoothly. It shakes and vibrate for 10-20 seconds and then it calms.
The car has 106000 km on the clock. What is strange for me is that the EML is coming back ussualy when the fuel tank level is below 1/4. I was thinking maybe the fuel pump is the problem, but not sure. And I mentioned that to the garages, but they said it's nothing to do with that. Also I mentioned that since I bought the car, I had to add coolant twice because the Low Coolant Level message poped on dash. Second garage said they found some faults on the thermostat, later to say that thermostat was good and just ignore it. Also they said that collant temperature sensor is faulty and needs to be replaced but they will have it in stock in few weeks.
Now I'm very dissapointed with these technicians and totaly lost faith in them. I feel like they would be happy to see me coming back more often. Already spent 2000 euro and I still can't find the problem. I thought that Mercedes Dealer should find the problem easier, being equipied with best diagnostics and technicians. Just not ready now to replace everything using poke method. Maybe it's something minor that some of you guys already experienced... Let me know if you have any sugestions please...Thank You

Sorry for long story...

 

See if MB (direct) will offer both technical assistance to dealer and goodwill assistance to you for adequate diagnostics since you paid for misdiagnosed repair: https://www.mercedes-benz.ie

 

Thanks Konigstiger...We'll definitely try and call them...
BTW In the meantime, a filled again the fuel tank and EML went off somehow, but the engine still doesn't run smoothly.

Regards