What causes light gray smoke from the exhaust?

When did you see this smoke? Initial startup, under throttle? Light grey is usually oil related but depending on when you see it can indicate the source. Also is it constant smoke or sporadic? Is this the first time you have seen it? What were the reasons for the plug and crank sensor change?
https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust

The sensor was going bad, and the plugs needed to be replaced. I noticed the smoke when I was backing up into my parking stall and I had the gas pedal on. This was the first time I saw this.

Was wondering if they were changed because you had misfires, the smoke could be related. However if it's only there on initial start up and then goes away until the car sets a while I would look at the valve stem seals. If it does it full time then it's more likely due to worn rings.

Yeah, it had been misfiring and that is why I changed the sensor, and I hadn't changed the plugs in 2 years. It happens after it has been running for a while. I went to the store which was less than one half of a mile away and on my return home when I was backing up into my parking stall is when I saw the smoke and there was a lot of it, and I shut down the engine. It was running better than it had been.

Okay, the misfiring might have damaged the engine some. The misfires can dump extra fuel into the cylinders and cause the oil to get diluted some as well as wash the oil off the cylinder walls and cause the rings to wear and then the engine starts burning oil.
I would suggest doing both a compression and leak down test on the engine to determine if that is the case. I suspect this more than other reasons because you say it starts smoking more as the engine warms up. That means as the oil gets thinner it can bypass the rings easier. One thing to try first, do the tests then change the oil and filter. Sniff the oil on the dip stick and see if it smells like gas as well. That would really indicate that it needs an oil change.

No, it doesn't smell like gas. So, I'll do the compression and leak down test as soon as I can, and I'll get back to you when I have the results. Thank you

Let us know what you find, we'll be here.

The smoke is gone, but now my car is starting to run hot and I'm always putting coolant in the radiator. I thought it might be the fan, but the fan is running. I don't have a clue what is wrong with the engine.

That isn't a good sign, using coolant and running hot is usually a head gasket issue.
https://www.2carpros.com/articles/head-gasket-blown-test