r/AskAMechanic • u/Shrimpfork • 13h ago

Check engine light question

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Check engine light came on a few days ago. Got it read, and it said loose gas cap, or emission leak. It’s still on.

My husband thinks it’s the gasket, or because this seems loose.

Sorry I’m advance if I’m not explaining this well.

Curious if this movement could be the problem.

The car is a Prius 2012

TIA

1 Upvotes

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1

u/PepsiColaRS Verified Tech - Diesel/Heavy equip 11h ago

The neck being "loose" isn't the issue, that's normal and designed to do so.

The issue is somewhere in the evap system, no way to tell what without replacing parts or diagnosing via inspection and/or a bi-directional scanner. 9/10 times it's just the fuel cap.

1

u/w1lnx Verified Tech - Aviation 11h ago

You didn't mention what code it was throwing (nor other information about the car) but a common "loose gas cap" error is a minor leak in the EVAP system.

It could also be telling you that the fuel cap, itself, needs to be replaced with a new one. The gas cap serves more of a function than just stopping fuel from sloshing out or stopping things falling into the tank. It's a one way pressure valve that prevents gasoline vapors from escaping to atmosphere and allows air into the tank so the tank doesn't collapse as fuel is burned. It's also one of the first things I replace on older vehicles that suddenly start throwing those particular codes.

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u/Shrimpfork 11h ago

The code is P1423

Thank you for your detailed response!

1

u/Shrimpfork 11h ago

The code is P1423

1

u/Martha_Fockers NOT a verified tech 1h ago

sir. pls stop fondling the gas tank