I have a 2013 Mazda 3 i Touring sedan, with about 39,500 miles on it. I've had no issues with it before. And I had a mechanic look it over about 6 months ago when I bought it.
This just started last night. While driving on the highway, my car thought that my key was not in the car. It then dropped to a lower gear while I was trying to accelerate. After a while the check engine light came on. I got off the freeway, looked up common issues, one is that the check engine light can come on if the gas cap is loose. So I tightened the cap, turned the car back on, and the light was off.
I continued driving, and then I had the same issue. This time I unscrewed the gas cap and put it back on. Tried this a few times, and the light was still on. Then this morning, when I was going to go to an auto parts store to get a code readout, the engine light was off. So I decided there wasn't much I could do about it. So I went grocery shopping, which required driving on the freeway. It was fine. But then when I drove home, the light came back on, and again I had issues with acceleration. I took it straight to an auto parts store, but when I turned the car on for them to read the code, the light was off again. Went home, and the light did not come back on.
The only thing different between when this issue started and before is that the temperature outside went down by 30 degrees (at the high) compared to Friday. Plus there's been really bad wind here, in the 25 mph range, with gusts up to 50 mph. But I can't think of anything else that's changed. I did get my wiper fluid filled a few days ago, but that seems very unlikely to cause an issue like this, unless Jiffy Lube did something weird when filling the fluid. I have also been meaning to replace my air filter. Though the filter isn't quite at the end of its life yet. Gas tank is a little more than half full. And the problem started when I had 3/4 of a tank. I also haven't heard any weird noises, as far as I can tell.
Any ideas what could be the issue?