P0451 error code (bad FTP sensor) 2011 Suburban

[njracer]

Short story...

I got gas on Monday and only drove a few miles and went home. Next morning used the auto-start and then headed off to a meeting. Came out of the meeting (it was snowing) so I went to auto start and nothing. Started the car and the check engine light came on. This was not on when I drove to the meeting. Had Auto Zone pull the code and P0451 came up. Guy said it was most likely the gas cap is not on correctly. Checked it and sure enough the plastic strap was wedged under the cap. Put cap on correctly and have use the truck a few times driving a good 15 to 20 mi.

So it looks like it's the FTP and going by what I can find on YouTube, this is something that I'm going to have to take to the dealer or local repair guy.

Couple of questions:

1. Is there an easy way to replace this or do I have to drop the tank?
2. Would the check engine light being on prevent the auto-start from working?
3. Also noticed that the AC light will not come on. If I press it it will light up, flash one or two time and go off.

Anything else I should check?

BTW, I've owned the truck since new and it has about 88K on the clock.

Thanks,

Brian

 

[njracer]

So...I disconnected the battery for a few minutes and now the check engine light is off, the AC works and so does auto-start.

I hope the error code was due to the gas cap not being on properly the other day.

Fingers crossed.

 

[swathdiver]

Yes, once a code is stored the engine cannot be remotely started for safety. Your truck went through a self-test while you were away and that is when the code set. A restriction in the vent lines or EVAP canister could set this code if it does not allow the valve to bleed off fast enough.

A Tech2 can be used to test voltage and command the valve on and off for testing Purge/Seal and Snapshot methods.

I do not think this is related to your AC. A basic code reader cannot see BCM codes, you need a good one or a Tech2 to help troubleshoot this and your AC.

 

[Rwayne]

Long story, short version.
Rough idle= cleaned maf, cleaned throttle body, new air filter, new plugs and wires. Truck runs nice but still has a rough idle in gear. P0451 popped up and im having a tough time finding a lot about it. I ordered the fuel tank pressure sensor and have cleared the code with my hypertech programmer. Waiting to see if it comes back.
Any luck with yours njracer?
Swathdiver, i'm gonna take your advice and see if j can find someone to diagnose with a tech2. Thanks