My gas fireplace turns on for a minute or so. then the flames turn blue as if lacking oxygen, then go out completely.

If the flame effect in your fireplace continues to stay on after turning it off, it could be due to a malfunctioning control board or a faulty switch. Here are a few steps you can take to troubleshoot the issue:

1. Check the remote control: If you have a remote control for your fireplace, make sure that it is turned off and that the batteries are working properly. Sometimes a faulty remote control can cause the flame effect to remain on even when the fireplace is turned off.
2. Check the switch: If your fireplace has a manual switch, check to see if it is in the off position. If it is not, try turning it off and see if the flame effect turns off.
3. Check the control board: If the remote control and switch appear to be working correctly, the issue may be with the control board. In this case, it is best to contact a professional for repair or replacement.
4. Unplug the fireplace: If all else fails, try unplugging the fireplace for a few minutes and then plugging it back in. This may reset the controls and resolve the issue.

It's important to note that if your fireplace is gas-powered and the pilot light is still on after turning off the fireplace, you should contact a professional to inspect the unit as this could indicate a gas leak or other safety concern.

Yellow flame indicates insufficient air is being injected into the mixing chamber - air hole blocked or restricted maybe.

Yellow flames indicate a general lack of oxygen and also a yellow flame is dangerous as it is producing high levels of carbon monoxide.

Looks like too much yellow in the flame. That is normally caused by the mixing control on the gas feed tube being too closed. Trace the tube from the burner .....back toward the gas feed line....until you find the slip ring that controls the amount of oxygen that is mixed with the gas. Open is a small amount and light it. You should see a bit more blue color. If that does not work, continue to vary the adjustment until the flame burns correctly. The pilot should never blow out unless the outside air feed is too large. You can try blocking it a small amount to see if the smaller amount of outside air corrects the problem.

This is a typical situation for a warn Powerpile generator. Your fireplace works by this generator generating heat from your pilot flame and converting it to less than 3/4 of a volt or 750mv. Your gas valve will eat up half of this electricity when running. So when you Powerpile gets warn it might only generate 400mv and when the gas valve turns on will bring it down below 200mv. This will start to drop once the main burner turns on and once below 150mv is no longer able to power the gas valve resulting in the main flame to go out. Minutes later the generator will build its power up again and repeat the cycle. The generator looks a little thicker than a crayon and has a red and white wire coming off it. They are easy to change but the tight spaces on a fireplace can make it very difficult.

Look for a flame sensor, It is a wire that is has to sit in the path of the flame. IT is gets dirty and can cause this. You can clean it with scotch brite pads

This is often a result of insufficient oxygen to allow combustion.
Check your venting for blockage.

Here's a few things to look for. After you light the pilot and turn on the burner, look at the pilot flame. Is it still a strong blue flame and it is still heating the thermocouple? If the pilot flame is a lazy yellow, it may not be able to keep a good enough flame on the thermocouple to keep it hot. The solution? Turn it all off and let it cool down. Take a can of compressed air, like you use to clean computer keyboards, and using the attached straw, blow out the dust or spider web that's partially blocking your pilot orifice. Where the pilot flame is usually lit, blow right down that flange, as well as through the air hole that is on the side of the pilot assembly. If you do it right, the pilot flame should be a nice and strong blue color. Another thought. Is this a vented or unvented fireplace? If it's vented, make sure it has the oxygen it needs to burn by checking for blocked vents or opening a closed fireplace fume above it.
Douglas

Do you have a remote that turns the unit on and off
and has different heat settings? Could be the batteries are bad in remote

your line mite be stopt up get a mach and turn on you gas and see if i lights up if it dont your eather out of gas or your gas holes whare the flame cums out is stopt up

Have it checked out by a QUALIFIED gas person!! Don't screw around with gas unless you want to wake up dead due to carbon monoxide poisoning or an explosion!!!! Gas is NOT a forgiving task-master.