Interestingly, this has just been posted on a MB Forum Eameez
"Mercedes C180K - 2006 (W203)
Engine M271
100,000 miles
My C180K will not start and if it does it sounds like a diesel tractor and runs rough. Can anyone help me detect the reason because due to Covid 19 i can't take it to a garage and i need the car to use to shop etc.
It all started the one morning when the car started up fine but had a rough idle. I could rev the engine cleanly but it would idle rough. I took the car on a drive and it was fine on the motorway for 30 miles but it still idled roughly when stationary. I then made the return journey about 2 hours later and the car ran fine again but still had an idle issue. Once i had reached my destination i tried to start the engine again about an hour later and the engine ran really badly and sounded like a diesel tractor so i immediately turned it off. I used my handheld code reader and got teh following codes:
P0301, P0302, P0301, but not P0304 All codes are listed as Cylinder Misfire Detected
P0325 - Knock Sensor 1 Circuit Bank 1 or Single Sensor
P0341 - Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor
I have replaced the Camshaft Position Sensor with a new one thinking that was the issue but the problem still exists
I called the roadside recovery company (AA Ireland) and they called out. He tried to start the engine but couldn't get it started. He took out all of the plugs and visually inspected them and none of them were damp or showed particular signs of wear. He tried to start the car again and he managed to get it started and but it was running really rough. He couldn't identify what the issue was and told me to take it to a garage and get them to stick it on their machine.
I do have very oily camshaft magnets. I took them off and cleaned the oil away. There was a trace of oil on one of the terminals which i have cleaned. I traced the wires back to the ECU and there was a small amount of oil at the end of a lead but i can't be sure if this is the camshaft magnet lead. I have seen online that i can test the magnet by attaching a 12v battery and placing an electrical meter inline to the magnet and then by moving a metal spanner around the magnet i should be able to see if the magnet generates a signal. I haven't done this yet but will try to do it next. I have no idea how to test the leads though so if someone can advise on testing that the leads to the magnet give a signal/volt then i would love to hear from you.
So basically, can anyone help diagnose my non-start and rough idle. I don't want to keep replacing potential problem parts with new ones as i don't have much spare cash following Covid work restrictions.
Thanks in advance for any help you guys can provide "