The code reading is P0455?

PAULINEHILL

MEMBER
2007 CHEVROLET IMPALA

It started out with a bad gas cap. Went to auto zone and they sold me the wrong cap that wasnt pressurized. I drove for 3 weeks like that. Put the right cap on and my code hasnt reset and now it states tha its gross evaporitive system leak.

Sunday, May 13th, 2012 AT 7:30 PM

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,
The code:
P0455 - Evaporative Emission (EVAP) System Large Leak

The code for the large/gross leak usually means that the fuel tank is unable to hold any pressure at all.
It can be from a faulty vent valve that is stuck open. Faulty pressure sensor or a damaged or broken pipe/hose of the EVAP system.

When you take off the cap for refueling, if you have hear the air rushing out of the tank then it is likely a pressure sensor that is faulty and needs replacement.
But then again that is not a fail proof test as many times the gas cap does not make much noise.

The fuel tank pressure sensor is located on the top of the fuel pump sending unit.

Also if you have the canister vent valve stuck open it will let all the fumes escape the fuel tank and trigger that light as well.

https://www.2carpros.com/articles/evap-system-code-repair

I have attached the diagnostics for that code as well as EVAP components for your reference.

Please let me know of any questions.
Thank you.

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