What causes the P0455 code in a 2006 Pontiac Grand Prix?

CapricornWoman_72 to answer your inquiry to In about the purge valve location on your car, see attached photo....

Missing gas cap

Charcoal canister vent valve stuck open

Possible purge solenoid stuck open

A smoke machine or vacuum pump is needed to diagnose it further.

Here are the most common problems that will throw the code:

Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. This will cause the P0455 code. Look for either a tear or hole in it. This is one of the most common issues that causes the code

Vapor Canister Purge Valve– One of the most common causes of the P0455 code is the vapor canister purge valve. It’s really easy to replace. There are a few clips that you need to find and remove.

Faulty Charcoal Canister– The charcoal canister is often the cause of P0455.

Fuel Tank Sending Unit– It is possible for the gasket that attaches the fuel sending unit to the gas tank to go bad. This can reduce tank pressure and throw the code.

Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. If you are getting that message, plus a P0455, it may save you a ton of time and money to replace the fuel cap and see if it goes away.

Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. This gasket can dry out, especially with vehicles that spend their time in dry climates. When it dries out, the fuel tank can’t hold pressure anymore.