The dealer cleared the code today. He checked electrical fittings and hoses. The code didn't return so he did nothing. He said Honda doesn't want them to change parts based on one code like this. It was indicating the cooling valve.
I'm not thrilled that this code came up, nor me being part of Honda's debug process. If this code/problem doesn't return Honda will consider it solved and won't record it as a fault. I do because I had a warning message for several days, had to schedule an appointment, and wait for two hours while they did things to my car.