Merc engine turns over but wont run


i had a code for this p0102/p0103 which indicated possible mass air flow sensor. i changed the MAF then like an idiot deleted the codes.
now i have no codes showing but the car still wont run. it starts, turns over but that's it. :oops:

i'm now thinking fuel pump/fuel filter?
any other thoughts from people who might actually know what they're doing? :xd: :dying: :dead:

Mercedes 2001 C class W203


Is this a komprossor model? they have a small vacuum ait pipe under the air filter housing that over time collapse and restrict air flow from the crank case breather, this would bring up a mass air fault as the readings would not correspond to the ecu values it is expecting.

Now as for the non start, that can be one of three things. three simple things an engine needs to run,
Compression, does the engine sound like it has compression, if the engine turns over extreamly fast with no resistance then compression would be your problem.

Fuel, every engine needs a fuel supply to run, check you have the correct fuel in the car, petrol/diesel, then at the fuel rail or filter check for fuel pressure. you can disconnect on of the supply lines and try with ignition on, and cranking, be carefull as fuel is flammable so if you see fuel cut power on the key immidiatly.
lastly speak (for petrol only) this is probably the hardest to check on a modern engine, as they mainly have coil packs on top of the spark plugs, no real simple way to test, however if you have a old spark plug lying around you could remove the coil pack and fit the spare spark plug in to it, rest it on a decent engine earth point/rocker box, and crank the engine and look for a spark.

hope this helps


Did the vehicle run before you code scan and replaced the maf?

If not, what was the recent history, i.e. poor starting, rough running, stalling at junctions / traffic lights?
If it did run before the replacement, it has to something directly connected to what you have done, so go back and re check everything you have disturbed. pipes, connections, etc

A little history would be helpful.


Thread starter
Yeah, ran slightly uneven for ages (over a year - please don't judge me!!) and would threaten to stall without actually doing so.
Then driving to work and got round the corner and it just stopped. Me and my pensioner neightbour (woman!) pushing it back down our street in the lashing wind and freezing rain to get it back on the drive where it has sat ever since.
Checked codes at that point and googled around and it seemed like MAF might be the culprit. But like I say that didn;t sort it.

Turns over well but doesn;t catch - normal starting tone/noise so compression is probably ok.
120,000 on the clock and always been a dead solid runner apart from my negligence.
Oh, had it in for MOT and whatever they did the cruise control suddenly stopped working but that was a while ago.