I have a 2007 Ford F-150 Supercab 4X4 with a 5.4L Triton engine. I've been "horsing around" with the engine light and the P0446 engine code. Several months ago, the light came on and showed the P0446 engine code. I took it to a mechanic. He checked all the circuitry and everything was O.K. He finally changed the solenoid, but the code still showed. So he put the old solenoid back in. His computer then died. When he finally got his new computer, the service engine light went out. It stayed out for a week, then went back on for a week, then stayed out for two weeks, then went on for a few weeks, always showing code P0446. This was happening for a few months, off and on and off and on. I am a very analytical person being an Enrolled Agent for ten years and currently an accountant. I figured there had to be a pattern and there is. I received the truck from my father in Yuma, Arizona, in 2014, which was a very hot and dry climate. Now in Wisconsin, it is in an exact opposite climate. Every time it rained, the light would come on and stay on, until I drove it a lot on the freeway and we would have very high winds (30mph sustained, 50mph gusts). Then one time, where the message center is, a "Check Gas Cap" message appeared. A friend told me to put Vasoline around the rubber gasket of the gas cap. IT WORKED! When it gets warmer, I am going to put Vasoline on all the rubber gaskets and seals: hood, doors, windows, etc. Vasoline is 100% petroleum jelly and restores the depleted moisture from rubber. Hopefully, it will seal something and maybe the engine service light will stay off.