Pulled Codes P0455

[ryhi]

so i got my CEL checked out n did a scan. P0455 Evaporative Emission Control System Leak Detected (Large) . has anyone had this code pulled from their car before? where do i start? mechanic said it could e a loose gas cap, but i think i remember reading somewhere on this forums that a loose gas cap has its own code? im not sure i tried doing a search but no luck. mechanic also said it could be a leak in a hose. i tried tightening the gas cap several times, ut no luck. CEL still came on and the gas light still blinks after driving for a while when im at a stop.

[kameraguy]

For this kind of stuff, I like to search mercedesshop as they are focused to technical problems. Try this link: http://www.mercedesshop.com/shopforum/search.php3?searchid=228822

Looks like a lot of info there :)

[jnenad16]

regeneration valve or one of the vacuum lines connected to it has a leak. regeneration valve is located under the washer fluid tank and is labeled "MOT"
you can start from there.

nenad

[SLAMMED_C]

PO455 is a general code for major leak in the purge system.. there is no seperate code for gas cap.. it will casue that code to be set in ME.
I havent seen very many problems with MOT valves, more problems with the white valve (charcoal cannister shut off valve) then anything else. and one time there was a problem with the fuel tank pressure sensor.. but a rare case I think.
did this happen after you filled up your gas tank at all?.. then in most cases it was the gas cap not reinstalled properly.
but my money is on the white shut off valve.. best thing to do is a full check of the purge system to eliminate each component.

[alboogiee]

for a gas cap, your car has to have the code either reset or you have to reset it manual, roughly turning the car on, driving about a mile, turn off, and repeat about 20/25 times, this is so the car will have a full rotation done to the code, if it is the gas cap... happend to my homies sebring convert...we were drivin up and down 80 forever stopping and going, but after like teh 20th time the check engine light went off... but for a light specificly for the gas cap i dont know...

[martattack]

I have reset my CEL by removing the negative terminal of my battery for about 10-15 minutes, then connecting.

[alboogiee]

Originally posted by BoominBenz
I have reset my CEL by removing the negative terminal of my battery for about 10-15 minutes, then connecting.

i suppose that would be the smaaart thing to do... :stupid:

[714guy]

Originally posted by BoominBenz
I have reset my CEL by removing the negative terminal of my battery for about 10-15 minutes, then connecting.

Even better, disconnect the battery, turn key to ON and turn steering wheel. this will drain all the battery right away. Then connect the battery. Start car and CEL should be off. Props to RENN208 for that.

[ryhi]

i already got the code cleared with the scanner, but the gas light still begins to blink after driving a bit.. HOPEFULLY its just a bad gas cap..

[alboogiee]

i know you are supposed to be able to clean it with something... or buy a new one, i dont know what the solutino is, i know there is a series of washers, sometimes if one is bad, then it leaks fumes and sets of the CEL

[714guy]

Originally posted by ryhi
i already got the code cleared with the scanner, but the gas light still begins to blink after driving a bit.. HOPEFULLY its just a bad gas cap..

just go to auto zone a get a new one, its like 10 bucks or the one from the deaer which is about 30 bucks. i know you won't pass smog with a leaky gas cap.

[ryhi]

is there a downside to running an aftermarket gas cap?

[714guy]

Originally posted by ryhi
is there a downside to running an aftermarket gas cap?

not that i know of, i had to replace mine a few years ago when i smogged my car, b/c it wouldn't pass

[ryhi]

and ur still running an aftermarket one?

[KenzBenz]

Originally posted by 714guy
not that i know of, i had to replace mine a few years ago when i smogged my car, b/c it wouldn't pass

same here, seems to be no problem

[ryhi]

blahhhh got a new gas cap today n still get the same problem.. :(

[ryhi]

where is the charcoal canister located? i dont get any air releasing when i loosen the gas cap.

[jnenad16]

it is under the driver's side fender, to get to it, you will need to remove the wheelwell cover, and to remove that you will need to take the wheel off.

nenad

[ryhi]

is this usually the cause of the linking fuel light and loss of tank pressure??

[ryhi]

anyone?? did anyone else go through this? help me please!

[jnenad16]

Originally posted by ryhi
anyone?? did anyone else go through this? help me please!

wish I could help you, but I have never encountered this problem before. One of my customers had the similar fault code, so I replaced the regeneration(MOT) valve and it was fine after that. did you inspect all the vacuum lines, the charcoal canister, and the check valves? thats most likely where the large leak could be. if you want to post your email, I could send you the evap system diagram, try tracing it and it might help you.

nenad

[jnenad16]

according to the last chart I emailed you, it looks like the fuel tank pressure sensor is bad. if I'm not mistaken, this sensor is actually a part of one of the fuel level senders in your fuel tank.

nenad

[ryhi]

would a sensor cause my car not to build up pressure though?

[jnenad16]

Originally posted by ryhi
would a sensor cause my car not to build up pressure though?
not sure what do you mean, but the fuel tank pressure sensor just measures the pressure inside your fuel tank. once it goes bad, it triggers the CEL and the fuel gauge light as well. it may or may not make your car run shiety, similar symptoms of a bad O2 sensor(poor performance and gas mileage). first, find out which of the fuel sending units has the pressure sensor installed in it, then try unplugging the connector on that sender. if nothing changes, than you know that is the problem. to do this, you will need to jack up the rear end of your car. at the bottom of the fuel tank, there are two plastic covers(one on each side of the driveshaft), remove the 10mm nuts that hold them, and now you should be able to see the bottom of the senders. unplug the connector on the sender that contains the pressure sensor, lower the car, and start the engine. if nothing changes, you found yourself the source to your problem.

nenad

[ryhi]

i still have this problem!! i forgot to mention that my cruise control doesnt go over 40 anymore!!! any ideas?

[istvan72]

I'm just wondering if you fixed the tank fuel pressure/blinking light/faulty cruise problem?
I have a '99 C230K and I have the same problem!
The car is still running fine but now I want to sell it,I must fix this before.
Thanks!
Istvan from Canada