Gas Cap Code (I've seen the thread started by GMERLIN)

As the subject says. I felt I had to start a new thread because I have a new question. His thread was almost 6 years old. Anyways so I am getting the gas cap code and I replaced it with a new cap. I cleared the code but then it just came back on. On my dash kept saying "tighten fuel cap." Anyways I had my mechanic replace my fuel pump since it went out on me several weeks ago. After getting it back, a couple days after that's when the gas cap code came on. My question is, could my mechanic made some error on the fuel pump installation? As stated before my gas cap code never came on before the new fuel pump. I need to know what to tell my mechanic so that way we can resolve the issue. Thanks a bunch!

Good morning mellowboy!
Is your mechanic with one of our GM dealerships? Understand if not - just wanted to offer to check into this further if you were working with us on it. :)

Sarah, GM Customer Service

The gas cap code just means there is a leak in the evap system and the cap would be the first suspect, but any leak in the valves or hoses in the system will set a code, based on what you say happened I would suggest that a line above or around the tank is cracked or pinched or loose. Not the fuel line but the evap lines.

Good morning mellowboy!
Is your mechanic with one of our GM dealerships? Understand if not - just wanted to offer to check into this further if you were working with us on it. :)

Sarah, GM Customer Service

No he's not affiliated with GM at all. Just independent mechanic. :)

The gas cap code just means there is a leak in the evap system and the cap would be the first suspect, but any leak in the valves or hoses in the system will set a code, based on what you say happened I would suggest that a line above or around the tank is cracked or pinched or loose. Not the fuel line but the evap lines.

Thanks! I will let my mechanic know.

Not a problem - all the best in getting this resolved!

Sarah, GM Customer Service

As the subject says. I felt I had to start a new thread because I have a new question. His thread was almost 6 years old. Anyways so I am getting the gas cap code and I replaced it with a new cap. I cleared the code but then it just came back on. On my dash kept saying "tighten fuel cap." Anyways I had my mechanic replace my fuel pump since it went out on me several weeks ago. After getting it back, a couple days after that's when the gas cap code came on. My question is, could my mechanic made some error on the fuel pump installation? As stated before my gas cap code never came on before the new fuel pump. I need to know what to tell my mechanic so that way we can resolve the issue. Thanks a bunch!

coming off the fuel tank are 3 lines. these are plastic. yes these can be broken when the tank is dropped.

when dropping the tank the larger vapor canister line that goes to the charcoal vapor canister can be broken at the input to this component.

this is very common when care is not taken in the tank dropping especially if the fuel is not removed before working this job !

the charcoal canister is expensive. the line if broken you can get an exact replacement at the dealership.

any fuel tank/canister leak will cause this code p0449 .

I doubt he screwed up the pump gasket locking ring or cracked the tank. the tank is strong. the lines and plastic nipples are not...........

when starting the vehicle every time the computer does a testing of all the vehicle systems. if the fuel tank has the incorrect pressure / vacuum you will get this code.

coming off the fuel tank are 3 lines. these are plastic. yes these can be broken when the tank is dropped.

when dropping the tank the larger vapor canister line that goes to the charcoal vapor canister can be broken at the input to this component.

this is very common when care is not taken in the tank dropping especially if the fuel is not removed before working this job !

the charcoal canister is expensive. the line if broken you can get an exact replacement at the dealership.

any fuel tank/canister leak will cause this code p0449 .

I doubt he screwed up the pump gasket locking ring or cracked the tank. the tank is strong. the lines and plastic nipples are not...........

when starting the vehicle every time the computer does a testing of all the vehicle systems. if the fuel tank has the incorrect pressure / vacuum you will get this code.

That sounds pretty accurate and I explained that to my mechanic. He's going to take a look at it tomorrow and hopefully this issue will get resolved. I appreciate your response!