Two words come to mind: broken wire. Check the output of the controller w/ a volt/ohm meter for a voltage slightly above 24V. Then start trying to figure out where the wire might have been cut in the yard.

My valves are immediatly adjacent to the house and the wires don't cross anywhere in the yard. The wires come directly out of the house into the valve boxes.

My first thought was that I may have hit something with the aerator BUT, the only thing I would have been near is the just the sprinker heads. Not anywhere even close to the valve boxes to cause any problems.

I will check the controller output this afternoon. Certainly would seem to be a broken wire but no clue on how to isolate it.

I checked the output voltage and it checked out OK. But the interesing this is the system mysteriously started working.

No matter what I did yesterday, I could not get the controller to open any of the valves. I must have left it in AUTO mode and sure enough, the morning I lookout the window and the system is working.

Hopefully it does not go down again but I suspect this is going to be an intermittent issue.

NC Lawn nut,

Sticky solenoid, but would only affect the particular zone. Unlikely all zone solenoids would have been sticky. Just a thought. Aloha,

Do you have a rain sensor?