We're offering our inexpert advice in all things automotive.
We might discuss your question on our podcast. Yes, this means that we've run out of ideas for episodes and are too lazy to do research.
Edit: Thanks for the questions everyone. We didn't have time to answer all of them on the show but I'll try to answer all of them on here. The episode probably won't be out for over a month since we've got a backlog of editing to do.
Maybe the battery in the sensor is running low?
Is 40 psi the recommended tire pressure? That seems high, unless it's on a truck or large SUV.
I personally have gone with 38 most of the time (toyota corolla). Maybe the weather is having some effect, but when I filled at a Speedway to 38 and it was still on. I suppose I'll lower to 36 in the morning. Thankya.