Check engine light keeps coming on

Hello,

When you say vary large leak do you mean for the EVAP system? If so then I would check the gas cap O-ring seal first and then the EVAP system vacuum and vapor tubes.

Here is a guide that will help you understand how the EVAP system works and what it does.

https://www.2carpros.com/articles/how-emission-control-systems-work

After you find the problem you must clear the codes.

https://www.2carpros.com/articles/check-engine-light-clear-codes

Please let us know what happens.

Best, Ken

Very common item that causes a large leak in the EVAP on these vehicles is the EVAP vent solenoid located under the rear of the vehicle. The solenoid shaft gets rusty and won't move far enough for the valve to close. That triggers a leak. The easiest way to test it is to use a scan tool with bi-directional controls and trigger it open/closed. You will hear it click. The next way is to disconnect it from the vent line, pull it off the bracket and use a couple jumper wires to test it using the battery.
It looks like the picture and is on the cross member behind the fuel tank. Great place to put an item that needs to stay clean and is supposed to keep dust and dirt out of the system. The OEM unit has a crappy "filter" in the box that gets gas fumes on it, then builds up with dust and then moisture. Then they stick open.