How long will the check engine light stay on before it goes out with no scanning or repair? This is on the 22 F-150.

 

indefinitely

 

Forever.

 

It depends on the cause and reason. You must pull the codes and see what's wrong and solve it before more serious malfunction come out.

 

In this case it went on Saturday and went out Monday afternoon. It was 3 or 4 startups after it first went on. Taking to dealer tomorrow for diagnosis. Had it in a few weeks ago for service and they found an old code. They didn't know what it was and cleared it..
During the winter there was snow on it so I took it to a self washer and sprayed off the snow. While driving afterwards the display stated that grill dampers were inoperative, probably froze from spraying off the snow. I believe the CEL did go on but went out soon afterward and I forgot about it until the service.

 

Service adviser said that apparently it was the knock sensor which are on backorder.

 

The check engine light was "programed" to turn on.
Now must be "programed" to turn off.

 

The CEL was off when I dropped it off this morning after it went on Saturday. No one touched it. It had been off since Monday afternoon.

 

The code is still stored even if the light turns off. Code scanners are cheap insurance these days. You can see for yourself what the code is and not be taken for a ride from shops.

 

Thanks, I thought they were stored until cleared by a scanner. Truck is still under warranty by the 3/36. The service adviser said that it still would have been covered under the 8/80. I've used this dealer for about 3 1/2 years now, they have done right by me so far.
I do have a cheap scanner but don't have it with me. I was just looking at scanners online.