First Check Engine Light @ 11,000 Miles: P0496/P0451

[RyanS93]

I'm curious did the fuel tank pressure sensor fix the issue? I am in the same boat right now. They have replaced both purge valve and the canister and the code came back after they replaced both of those parts. The fuel tank pressure sensor was on back order when they determined that was the next part they would throw at the issue.

I believe the part just arrived at my dealership, so fingers crossed no more CEL after they replace that part.

I have an appointment in a couple weeks to have this replaced but I am nearly 100% confident it will fix it as it has fixed it for other people on here.

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[huunvubu]

(1) Ford P0451 Check Engine Light after Krown Rustproofing - YouTube

Instead of doing an "Insert Link" to YouTube videos just put the link directly as text like this:

 

[gp1200x]

It would be nice if someone actually took a picture of what and where the purge valve and fuel tank pressure valves are located on the truck. I need to look at them before taking my truck in since I used waxoyl on my underneath last year...but that was 16K miles ago.

Updated...I went underneath and removed covers and found what appeared to the the fuel tank pressure sensor. It is part of a hose assembly (1.5 ft long) listed earlier (new part number NZ6Z9D333H) and the sensor is a part of the hose. I don't know if you can actually buy just the sensor..I doubt it. Mine looked okay but I used mass air flow cleaner on it and also sprayed the two open orifices. I did not see any of my waxoyl clogging any part of it and connections were clean. There was also a sensor of some type on the canister itself nect to where that hose attached. I pulled that sensor and cleaned it also. Very close to the fuel tank pressure sensor is a round pressure sensor on the fuel line - may help you to easily find the fuel tank pressure sensor.

I also tried to find the canister purge valve which is suppposed to be up near the engine. There is a small round canister on top of the engine that looks like it has a power connection and appears to connect back underneath the car however it has a hose to the intake in front of the throttle body. The makes me think this is not the canister purge valve since they usually require an engine vacuum connection to work.

Lastly I cleaned the gas tank filler valve and made sure it closed properly with some seafoam cleaner.

I doubt any of these will fix the issue but I will know in a day or two. My warranty work better be free since my waxoyl was not the reason for this error code.

Ford parts manuals not a big help and neither was rockauto for identifying sensors. This is a round differential pressure sensor listed on rockauto and it looks a lot like that fuel line pressure sensor but they are not the same. I have no idea where this differential pressure sensor is located ...fuel tank, engine, ?? It is round and threads into a body like an old oil pressure switch .

 

[gp1200x]

NY owners.... I was worried about the check light coming back on before I could get it inspected after resetting the tests. In NY you can have one test incomplete and pass but the check light CANNOT be on. I took it to have it inspected after getting all but the EVAP tests completed. Let it running while waiting for them to get to it since I read that turning it on and off increases the likelihood of the P0451 getting set.

To my surprise they have it inspected in 5 minutes and it was only $10. For the one year old inspection in NY they DO NOT use the OBD connection and no exhaust check. It is only a safety inspection so even if the check light was on it would not have mattered for this inspection!

 

[gp1200x]

3 days, 300 miles and about 20 starts with no new P0451 codes or pending codes. Maybe it is fixed. Evap system registered OK after about 30 minutes of driving.

I sprayed mass air flow sensor cleaner all over the sensor and multiple times with the red tube directly into the two small 1/8" channels facing downwards towards the ground. I couldn't tell if these are open airways to the sensor or just a hole for possible mounting screws...not enough light.

 

[dragon]

I hit the same issue with a p0496 last month at 39k miles on my 22 Lariat. Ford replaced the purge valve and this was not covered under powertrain warranty. Today, 15 days later I get p0451. This looks likely the same problem. Does that sound probable?

 

[Beamcrazy]

It would be nice if someone actually took a picture of what and where the purge valve and fuel tank pressure valves are located on the truck. I need to look at them before taking my truck in since I used waxoyl on my underneath last year...but that was 16K miles ago.

Updated...I went underneath and removed covers and found what appeared to the the fuel tank pressure sensor. It is part of a hose assembly (1.5 ft long) listed earlier (new part number NZ6Z9D333H) and the sensor is a part of the hose. I don't know if you can actually buy just the sensor..I doubt it. Mine looked okay but I used mass air flow cleaner on it and also sprayed the two open orifices. I did not see any of my waxoyl clogging any part of it and connections were clean. There was also a sensor of some type on the canister itself nect to where that hose attached. I pulled that sensor and cleaned it also. Very close to the fuel tank pressure sensor is a round pressure sensor on the fuel line - may help you to easily find the fuel tank pressure sensor.

I also tried to find the canister purge valve which is suppposed to be up near the engine. There is a small round canister on top of the engine that looks like it has a power connection and appears to connect back underneath the car however it has a hose to the intake in front of the throttle body. The makes me think this is not the canister purge valve since they usually require an engine vacuum connection to work.

Lastly I cleaned the gas tank filler valve and made sure it closed properly with some seafoam cleaner.

I doubt any of these will fix the issue but I will know in a day or two. My warranty work better be free since my waxoyl was not the reason for this error code.

Ford parts manuals not a big help and neither was rockauto for identifying sensors. This is a round differential pressure sensor listed on rockauto and it looks a lot like that fuel line pressure sensor but they are not the same. I have no idea where this differential pressure sensor is located ...fuel tank, engine, ?? It is round and threads into a body like an old oil pressure switch .

Thanks for this, going to go hunting for my sensor this weekend.

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