I have a problem with my Rachio 3. The valves activate, but after the timer expires, they continue to work.
I tested the voltage on all zones when they’re not active, and it shows 12V, and when they’re active, it shows 24V.
If I turn off Quick Run, it shows 12V and they continue to work, but they don’t turn off.
It isn’t unheard of to see some voltage on a zone wire depending on the surroundings. You can get phantom voltage from other electrical utilities due to “capacitive coupling”. 12v seems a bit high for phantom voltage, and honestly probably isn’t enough to actually acuate the solenoid, but try unplugging the controller and see if that changes anything.
Otherwise, you may have issues with the valves or solenoids themselves. Diaphragms could be damaged or have debris in them.