Code p0442
 

What is it

https://www.rx8club.com/series-i-tech-garage-22/rx-8-technical-info-cel-codes-pcm-pin-list-collision-guide-26291/
Search for P0442 and you'll find the answer, but its usually the gas cap.

How long until the cap is either tightened or replaced should the CEL disappear?

I fear that my issue may be something other than the cap--especially since I powerwashed the engine bay on Saturday, and the code first appeared today...