I flled the tank with gas and 5 minutes later the service light came on. in the manual it states the gas tank cap could be loose or bad gas. the light stays on even after the cap was tightened. the manual states it may reset? it is not binking what to do? i did put in a gas treatment an car doesn't have any issue

Check the gas cap and make sure it is tight, if cross threaded or the seal is bad the light will kick on. Hope this helps.

Disconnect the battery for 3-5 minutes

If the code would have been due to the cap problem then the code will go away. Try resetting the code. Also try diagnosing again after disconnecting the battery and then reconnecting it after a few minutes.

P0440 - Evaporative Emission Control System Malfunction
Possible causes- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking Tech notes Loose fuel tank filler cap is the most common cause that triggers the P0440 code.

Your code, assuming it was evap related, also means other issues aside from a loose gas cap. Your fuel system "closes" down to purge unburned fuel back through the engine. A loose gas cap will stop this process, as in why the check engine light will go on. Also, there is a vent solenoid, purge solenoid, fuel tank pressure sensor, and a charcoal canister that are involved. My guess, but if you have a bad vent solenoid, you may have symptoms like yours. Any "good" technician can test this for you.

This probably means:

• P1456: Evaporative Emission Control System Leak Detected (Fuel Tank System)
• Usually this is because your gas cap was not fully tightened. Be sure to turn it until you hear a click.
• After you tighten the cap, it might take a couple days of driving before the light goes-out.
• Be careful to tighten your gas cap regularly, because otherwise it puts a heavy strain on your emission system.

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You may have a fuel tank vent valve that isn't working. This valve lets air into and out of the fuel tank as fuel is added to the tank and then later used by the engine. If the valve won't open or is plugged with dirt/dust/debris then it's becomes very difficult to add fuel to the tank. This problem would also cause the EVAP system to fail a self test and turn on the check engine lamp with a related service code. Often there is more than one reason a particular code like this can be set, a loose fuel cap being just one of them, and it takes a bit of testing to determine the exact cause. A good service facility should be able to test the system and determine what is wrong fairly easily on this one. Good luck, hope this helps.

The gas tank and emissions are under vaccum and a loose/bad seal or missing gas cap allows the vacuum to leak out when the pcm detects irregular vacuum it will turn the service engine light on.

You gas cap is not on tight enough to seal causing the Check Engine Light to come on. When you tighten your gas cap you need to tighten it until it clicks at least 5 times, if it is tight than the seal on the gas cap may be bad. Replace with a OEM GM gas cap or a quality replacement that meets OEM specs.

A loose gas cap will sometimes trigger the service light to come on.  Since this appears to have happened on multiple occasions I can assume that this is not the problem but may be associated with it.  The level of gas in the tank affects the amount of atmospheric pressure in the tank. There are multiple things that could set off the light, one being a loose or defective gas cap, and the other is a fuel vapor return valve.  I'm not sure of the exact type of fuel system you have so I cant give a more exact answer.  If you wanted to give something a shot before bringing it into the shop, you can simply replace the gas cap first, a very cheap try.