emission code p0440 and p 1665

faild emissions for code p0440 and p1665 arew they for the same problem
1999 pontiac grand am v 6

I would lean towards them being related as the po440 code is determining that there is a large leak in the EVAP system.

And the p1665 is for the EVAP solenoid valve is not within range.

Take care of the po440 code first and see if that puts the solenoid valve back within range. The solenoid opens and closes a valve that either vents or purges the EVAP system which basically lets fuel vapor circulate through the gas tank and intake system. This valve is controlled by metered vacuum.

I've learned that IF no one has been under the hood messing with stuff then the p0440 code is usually set due to a bad gas cap or faulty fuel lines on the top of the gas tank. I'm talking about all the little gas hoses...the vacuum one's don't have hose clamps...I usually put clamps on all the hose's.

Many EVAP system faults can cause a P0440 to set. A faulty EVAP Vent Solenoid may cause a P0440 to set. A P1665 is an Evap Vent Solenoid specific code. It indicates an improper voltage level has been detected on the output circuit which controls the EVAP Canister Vent Solenoid Valve. The vent solenoid or its circuit is what you should focus on first. A vent that won't close when commanded to will cause a large evap. leak and a P0440 because it cannot seal the system.