Sudden misfire P0456 code
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Joined: Mar 2015
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C55 AMG
Sudden misfire P0456 code
I have searched the forum and have found that the code P0456 pertains to either a bad fuel pump, sending unit, leaky gas tank seals, purge valve, gas cap or the filler neck assembly. So here is what led up to the misfire...
Yesterday I was gassing up and the pump kept stopping as if the tank was full, it wasn't as I had a half tank of gas to start with. I finally got it filled up and drove 50 miles each way to a family function. The car drove fine but today on my way home from work it stalled as I was driving up my street, I coasted into my driveway and it died. It has been raining here and I did not get a chance to start pulling things apart and thought I would post this here and hopefully someone has had the same issue and can chime in. Does this sound like a faulty filler neck? I see the 2005 C class cars have had this issue but have not seen the C55 with this or maybe it has? I will try and pull the seats tomorrow and look for the tell tale fuel sitting on the sending unit as i have smelled gas outside the car once or twice in the past but never inside. Hope someone can help at least with why I could not gas up without the pump stopping over and over...Thanks
Yesterday I was gassing up and the pump kept stopping as if the tank was full, it wasn't as I had a half tank of gas to start with. I finally got it filled up and drove 50 miles each way to a family function. The car drove fine but today on my way home from work it stalled as I was driving up my street, I coasted into my driveway and it died. It has been raining here and I did not get a chance to start pulling things apart and thought I would post this here and hopefully someone has had the same issue and can chime in. Does this sound like a faulty filler neck? I see the 2005 C class cars have had this issue but have not seen the C55 with this or maybe it has? I will try and pull the seats tomorrow and look for the tell tale fuel sitting on the sending unit as i have smelled gas outside the car once or twice in the past but never inside. Hope someone can help at least with why I could not gas up without the pump stopping over and over...Thanks
MBWorld Fanatic!
Joined: Feb 2010
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From: Bolingbrook Illinois
1999 C43 Amg
I have searched the forum and have found that the code P0456 pertains to either a bad fuel pump, sending unit, leaky gas tank seals, purge valve, gas cap or the filler neck assembly. So here is what led up to the misfire...
Yesterday I was gassing up and the pump kept stopping as if the tank was full, it wasn't as I had a half tank of gas to start with. I finally got it filled up and drove 50 miles each way to a family function. The car drove fine but today on my way home from work it stalled as I was driving up my street, I coasted into my driveway and it died. It has been raining here and I did not get a chance to start pulling things apart and thought I would post this here and hopefully someone has had the same issue and can chime in. Does this sound like a faulty filler neck? I see the 2005 C class cars have had this issue but have not seen the C55 with this or maybe it has? I will try and pull the seats tomorrow and look for the tell tale fuel sitting on the sending unit as i have smelled gas outside the car once or twice in the past but never inside. Hope someone can help at least with why I could not gas up without the pump stopping over and over...Thanks
Yesterday I was gassing up and the pump kept stopping as if the tank was full, it wasn't as I had a half tank of gas to start with. I finally got it filled up and drove 50 miles each way to a family function. The car drove fine but today on my way home from work it stalled as I was driving up my street, I coasted into my driveway and it died. It has been raining here and I did not get a chance to start pulling things apart and thought I would post this here and hopefully someone has had the same issue and can chime in. Does this sound like a faulty filler neck? I see the 2005 C class cars have had this issue but have not seen the C55 with this or maybe it has? I will try and pull the seats tomorrow and look for the tell tale fuel sitting on the sending unit as i have smelled gas outside the car once or twice in the past but never inside. Hope someone can help at least with why I could not gas up without the pump stopping over and over...Thanks
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Thread Starter
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Joined: Mar 2015
Posts: 31
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C55 AMG
speed43...Thanks for the info! Did you have the same symptoms with a rough misfire? I just went to try and start the car and now the starter just cranks and does not start...not getting fuel so the pump could be shot. I also removed the covers over the fuel pump and sending unit and there is no fuel sitting on top of the sending unit.
edit: the check engine light did not come on
edit: the check engine light did not come on
Last edited by DamienLBC; Jan 15, 2019 at 01:08 AM.
MBWorld Fanatic!
Joined: Feb 2010
Posts: 1,506
Likes: 130
From: Bolingbrook Illinois
1999 C43 Amg
speed43...Thanks for the info! Did you have the same symptoms with a rough misfire? I just went to try and start the car and now the starter just cranks and does not start...not getting fuel so the pump could be shot. I also removed the covers over the fuel pump and sending unit and there is no fuel sitting on top of the sending unit.
Thread Starter
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Joined: Mar 2015
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C55 AMG
Another thing I noticed that when getting on the throttle I get the rotten egg smell...I’m not getting a cel for the catalytic converter. After hours scouring the internet it can be a number of issues. I’m at work now and hope to get on it later, things to check will be the purge solenoid, charcoal canister and check to see if I can hear the fuel fuel pump work when turning the ignition. Thanks again for your input!
Thread Starter
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Joined: Mar 2015
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C55 AMG
So...it was the bad fuel pump and why the car died. I ordered one from my local MB dealer and installed it today and the car fired up right away!
It stopped raining so I had a chance to remove the right rear wheel and liner, the liner has a tear right across the top center so I put a bandaid on it using zip ties and a new one will be ordered asap. The filler neck and hoses all looked to be ok but after reading numerous threads a new one might be needed if I can't fill up due to back pressure. There was some dirt and debris in the vapor canister's purge valve due to the torn liner letting dirt behind the liner. I cleaned the dirt out with what I had on hand...throttle body cleaner and will wait to see what happens with the P0456 code.
It stopped raining so I had a chance to remove the right rear wheel and liner, the liner has a tear right across the top center so I put a bandaid on it using zip ties and a new one will be ordered asap. The filler neck and hoses all looked to be ok but after reading numerous threads a new one might be needed if I can't fill up due to back pressure. There was some dirt and debris in the vapor canister's purge valve due to the torn liner letting dirt behind the liner. I cleaned the dirt out with what I had on hand...throttle body cleaner and will wait to see what happens with the P0456 code.
