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My check engine light keeps coming on for "CHECK GAS CAP". I have changed my gas cap with a brand new one. And it came back. I know its not the gas cap. Does anyone know what this could be and how to fix it? Thanks for any assistance.

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I edited the title of your thread to remove the caps and multiple exclamation marks. That type of writing is unnecessary. I also added your year and model to the title to be more descriptive and show the AGE of the vehicle.

Check the pipe that runs from your fender to the gas tank for holes and leaks, we have seen them rust out. Put your nose under the RR wheel well and smell for fuel, if you smell fuel you probably have a fuel and vacuum leak from that pipe

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I edited the title of your thread to remove the caps and multiple exclamation marks. That type of writing is unnecessary. I also added your year and model to the title to be more descriptive and show the AGE of the vehicle.

Check the pipe that runs from your fender to the gas tank for holes and leaks, we have seen them rust out. Put your nose under the RR wheel well and smell for fuel, if you smell fuel you probably have a fuel and vacuum leak from that pipe

So if there is holes and leaks, does that whole gas tank have to be replaced? Or, is there a way to seal the leaks? If I don't smell gas or see rust, what would be my next step?

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Look for anything that would cause you to lose vacuum back there, hose, seal, rusted tank, pipe,

Maybe a member has seen this and can suggest what else can cause this

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The EVAP (Evaporitive Emission) system pulls fuel vapors from the tank and stores them in a canister to be burned. The line runs from the tank to a canister and then to a solenoid and valve on the rear cam cover. From there a line runs to the intake manifold or the TB. You need to check all those vacuum lines.

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The EVAP (Evaporitive Emission) system pulls fuel vapors from the tank and stores them in a canister to be burned. The line runs from the tank to a canister and then to a solenoid and valve on the rear cam cover. From there a line runs to the intake manifold or the TB. You need to check all those vacuum lines.

Would those be the 3 silver lines running under the middle of the car?

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