Hi. Trying to troubleshoot a P0451 code on my 2011 Ford Fusion SE - 2.5L -- "Evaporative Emission System Pressure Sensor/Switch". Previously replaced the purge valve solenoid and the vapor canister vent solenoid. From what I've read it seems that it could be the fuel pressure sensor or a leak from the gas "cap" area. Does the Fusion have the fuel pressure sensor built into the fuel pump? have people replaced the pump as part of a P0451 issue? I wanted to see if anyone else had experience with this before I bring it into the shop. Any help would be greatly appreciated!

Thanks!

 

From your description, you replaced the purge valve, but did you check to see if it is getting the signal to work?

Certain conditions are required for the PCM to send the signal for the purge valve to do it's job.
Those conditions need to be verified to be available to the PCM or it either is not getting the info,it may be getting the info and sending the signal and the purge valve is not responding. That is the path that should be verified before replacing anything.

 

Thanks Hanky for your reply. That is a good point and I attempted to check the signal using Forscan. Within Forscan, the only thing I can control is the Evap Canister Vent Valve and the Evap Purge Valve Duty Cycle. When I toggle the duty cycle I can track it with the Forscan Oscilloscope. However, when I try to turn "On/Off" the Evap Canister Vent Valve, I get no reading on the Oscilloscope. Should that be detected by the system? or are there other factors that need to happen first? With the P0451 code, after resetting it, it takes about 100 miles of driving to kick back on again. I am wondering if you had any resources on how to verify the other conditions available to the PCM? Should I drive it for a while and then run the Evap scan again? (see Evap Scan jpg image).

Thanks again for your help!

Evap CV Control vs Reading

Evap Systems Test