I have a 2014 c250 w204. Initially I was getting codes p0441 and p0451 with an intermittent check engine light. I replaced the gas cap (orig looked fine though) and that didn't change anything. Dealership replaced purge valve a few years ago, so I skipped that. Next I replaced the tank pressure sensor. After doing that the codes changed to: p0442, p0451, and 2422. Today I checked the purge valve, and inflow is blocked with car running or off. I connected 12 volts to the purge valve directly and could hear the click, and inflow it was no longer blocked. I then tested the connector with acc on and saw 9V, and then again with car running and got 12.25 V. If the connector has 12v with car running and purge vale opening with 12 volts hooked directly up, then what could the issue be? I included some pictures.

 

Did you use Mercedes sensors that you changed or aftermarket ones? Non Mercedes sensors will sometimes cause can buss errors and throw codes sometimes.

Also purge valve or purge system leaking sure will throw that code so a smoke leak test may be in your future.

 

Photo looks like one of the purge valve clamps is not connected and one seems to be missing.

 

I hadn't noticed that before but now that you mention it, theres another clamp missing from the purge valve out to the engine intake. Dealership must have decided not to put them back on.

I am mostly stumped by the purge valve working when direct 12 v is connected to it, but doesnt work when I connect the harness to it and run the car. I did check the harness and its giving 12.24 v. Connectors look clean....

 

My scanner has a function to activate the purge valve. I would use that function to test it.

Tank pressure sensor. Is it Genuine Mercedes or OE brand replacement? When I see codes like that, short to ground/positive it could either be a faulty part or faulty wiring. I recently had those same codes for my fog light, the bulb was fine but when I tested the connector the ground wire was faulty. I have no idea how the ground wire went bad so ran a new ground wire and fixed it.

Can you test the sensor connector for voltage and ground.

The purge valve code could be those loose hoses.

 

Thank you Tim for all of that information! It took a while to get back to you because right at that time I had just put in a new aftermarket fuel pressure sensor. After reading your message I ordered an oem fuel pressure sensor from Autohaus and when it finally came I swapped the other one out. Its been about 8 drives since and I am still getting codes: 0442, 0451, and 2422. I didn't start getting 2422 until the first time I swapped out the fuel pressure sensor. I am tempted to put the original one back in to see if that 2422 goes away--so much gas squirts out when I pull it off, so Im hesitant to do it again...

I have an OBDEleven gen 3 reader that I don't believe allows me to activate or deactivate the purge valve. It does have live data but i have no idea what those sensors are on it and what to do with the info as of yet.

I am going to put some clamps on today to those hoses that are missing them and see if anything changes from that.

If there is a wiring problem, how do I go about testing the fuel pressure sensor harness?

Thanks again!

Chris

 

Are there really two fuel pressure sensors and which one is the problem with the codes 0441, 0442, 0451, 0452, 2422?

I replaced the fuel pressure sensor thats accessible from on top (under back seat, drivers side) twice, no change. The other fuel pressure sensor supposedly needs the tank lowered to access it.

 

What is your vin#?

 

I dont have access to the 2014 C250 manual so im trying to use comparable manuals but dont know what engine you have or what parts diagrams to look thru.

If the code is for the B4/3 fuel tank pressure sensor it looks like its on the top of the tank in the middle. Not the sensor near the pump/filter.

 

Here’s the VIN

• WDDGF4HB1EG231763