fuel tank pressure sensor assembly on 2005 Ford Mustang

I have a 2005 mustang g.t., the service engine light is on, had a tech check and he said the fuel tank pressure sensor assembly shows a problem, also the fuel fill shuts off when filling the tank, are these problems related and what is involved with changing the pressure sensor assembly?

by in Clinton Township, MI on October 07, 2009
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2 answers 3 comments
ANSWER by , October 08, 2009
The tank filling issue is not a pressure sensor issue. When you fill your car, the key is off, so the sensor is not even 'on line' so to speak. That sensor is only to check for Evaporative System Leaks. The tank filling issue could very well be a defective vent valve or solenoid or a stuck roll over valve or even, in some cases a saturated carbon canister whose carbon pellets have plugged up the vent valve etc. ( common on other cars ) this is often caused by folks who 'top off' their fuel tanks i.e. just keep filling and the nozzle keeps clicking. Most folks don't realize that this does real harm to your emissions system and can cause very expensive problems.
COMMENT by , March 24, 2011
Good comments. dvb
ANSWER by , October 07, 2009
These are likely related, and I would not go changing the tank pressure sensor, I think you have another issue. The fuel filling issue may be due to a plugged venting system, which will cause the tank pressure readings to be inaccurate. Can you post which codes you pulled from the engine module?
COMMENT by , October 08, 2009
The diag-code performed by the dealer is -0451 and P1450-perform pinpoint test identify fuel tank pressure sensor assembly etc.
COMMENT by , October 08, 2009
You can read about the P0450 DTC here: http://repairpal.com/OBD-Code-P0450 The way to diagnose these systems is to have a very clear understanding of how the system performs it's self-diagnostic test, then monitor the sensors with a scope while the test is being performed. I'm still am leery of the fuel filling issue, a bad tank pressure sensor will not have an effect on that, so I think that is related. Let me know what you find out!