My unit had been functioning fine, suddenly 2 zone no longer go on
How many zones in total are you using? What is the layout, for example, how many boxes are there and are the 2 zones in the same box? Has any digging, etc., occurred lately? It seems what when more than one zone goes out at the same time, it is an issue with digging or a ground wire issue.
It is 2 zones on a separate box. I did have work done on the valves in the zones in one box
Are you saying you had work done in one box and then the separate box with the 2 zones are now not working?
If so, I would guess that the wires might go from the first box to the second and something happened with at least one wire. I could be wrong though.
I will look for a disconnected wire
Some times, it might be be terribly obvious as it could be not making a good connection inside the, hopefully, waterproof wire nut.
That makes sense. I will double check the connections