Do anybody know how to correct this code P0451, it has something to do with the emission. It's a hose or is it a sensor that needs replacing? thanks

 

I'm no expert, but if the code is the evap system, it could be as simple as a gas cap that doesn't seal and hold a vacuum.

It may also have something to do with the purge valve to the charcoal canister. The one on my Ranger bit it last year and threw an evap code. Repair parts were a whole kit with hoses for the Ranger, not terribly expensive from what I remember.

 

thank you I will replace the gas cap and hoses

 

Is your message center (the LED display) displaying CHECK FUELCAP? If not it's probably not your gas cap. Did you pull the code with a reader? And is your check engine light on?

P0451 Evaporative Emission Control System Pressure Sensor Range/Performance

This code has to do with a control system pressure sensor being out of range or reacting too slow or too fast. l do not have my manual handy to tell you what to troubleshoot. But I would not start randomly replacing hoses and caps. You could end up masking or causing other problems.

 

Wildcard30, I don't have a led displaying. And yes I had the code pull with a reader and my check engine light is on. I have a 2004 f-150 xlt with about 95500 miles on it.

 

Is it a 2004 heritage, or the new (current) body style? What engine do you have? Is it a 5.4?

 

My truck is the new body style 2004 with the 4.6L engine. It is the XLT style.

 

A guy that I work with was getting that same code on his 04 xlt 4.6.In his case he said it was a bad fuel tank pressure sensor.I don't recall if it was located on top of the tank or in the tank but they had to drop the tank to get to it.
In your case it may not be the same problem he had but it may be something worth looking into where your getting the same code.

 

thank you nassty I will try to find that part and replace it.

 

Are you having a specific problem? Is the truck running poorly? And if you are having problems, when are they happening? Truck cold, truck hot, after filling gas tank, when idling?

Give us some more info please.

Spend a few dollars on a good shop manual. You can "replace parts" from now until Christmas and not find the bad sensor. You will eventually find the bad part, but you may end up replacing most of your emissions sensors in the process.

It would suck if you replaced $100.00 in parts and not get it fixed. But if you were to spend 20 bucks on a manual, it would help you troubleshoot it down to the correct part.

I found some additional info for ya...

<table align="center" border="1" cellpadding="3" cellspacing="0"><tbody><tr><td nowrap="nowrap">

P0451
</td> <td> Fuel Tank Pressure Circuit Noisy

</td></tr></tbody></table>
So it could be as Nassty says. Or you could have bad wiring, causing noise on the circuit, even a tank venting problem. Do you overfill the tank so there is fuel in the neck?

Here's some info I found on another site... (edit: The following info is from the Ford OBD manual)


The Fuel Tank Pressure Sensor input circuit is checked for out of range values (P0452 short, P0453 open), noisy readings (P0454 noisy) and an offset (P0451 offset).

The offset test is new for the 2004 MY.

Note that carryover 2004 MY software and 2003 MY and earlier software will set P0451 for the noisy sensor test. Note that an open power input circuit or stuck check valve generates a P1450.

Let us know what the truck is doing....

 

Good advice, I will purchase a manual today at Advance Auto. The engine is running fine. I haven't filled the tank up in a long time.

 

I just keep finding additional info...

This is from the Ford OBD manual:

Fuel Tank Pressures Sensor Offset Check Operation
DTCs P0451 – Fuel Tank Pressure Sensor Range/Performance (offset)

Monitor execution once per driving cycle
Monitor Sequence No P0443 or P1450 DTCs
Sensors OK
not applicable

Monitoring Duration < 1 second

Typical Fuel Tank Pressure Sensor Offset Check Entry Conditions:

Entry condition Minimum/Maximum

Ignition key on, engine off, engine rpm
0 rpm

Purge Duty Cycle
0%

Engine off (soak) time
2 hours

Battery Voltage
11.0 Volts

Typical Fuel Tank Pressure Sensor Offset Check Malfunction Thresholds:
Fuel tank pressure at key on, engine off is 0.0 in H2O +/- 2.0 in H2O

Here's the link to the OBD manual, it is a download in .pdf format.

Motorcraft Service

 

I don't understand how to read this. What is it saying.

 

It's the procedure to test for a problem with Fuel Tank Pressure Sensor Range/Performance (offset).

You need an instrument that can monitor the OBD PID loops real time. This info is more detailed then a Haynes Manual.

Use the link to download the ODB manual. It has more explainations on the OBD system and codes.

 

Wildcard you will be surprise to what made the check engone light go out. I waited to my tank was about empty and I bought a gas treatment by Vavleline that cleans emission and then went and put some gas in the truck. One day later after the treatment went through the light went out. Wow. Thanks