Since the code was P1637 H, the good news is that you do not currently have this problem but the bad news is it may come back, if only for a long enough time to trigger the code again.
I first got the P1637 code 18 months ago and have been trying to permanently get free of it ever since. At times, it will go away for months but it always comes back.
Using my service manual, Tech2, test lamp and DMM, I have followed the diagnostic procedure so many times I don't need the book anymore. I have inspected, cleaned and tightened all connections several times to no avail. For awhile, I had the charge system fault message as well but cleaning the connection at the starter solved that.
The one abnormality that has remained constant is that the "generator sense circuit", which is the S terminal on the generator will not light a test lamp as it is supposed to do. Unfortunately, I can find no info in the manual as to the remedy, nor a diagram of it.
The output of the generator at the output terminal has always been normal. I have come to the point where I'll either choose to ignore the code or replace the engine wiring harness, which is very expensive.
Hopefully, your code won't come back or if it does, You'll be able to solve it easily