Sprinkler Solenoid Problems: Symptoms and Fixes
That black cylinder with two wires on top of each sprinkler valve is the solenoid — the part that translates the controller's electrical signal into opening the valve. When a solenoid fails, the zone won't work. Here's how to spot and fix solenoid problems.
What the solenoid does
When the controller energizes the solenoid, it opens a tiny port that lets water pressure lift the valve's diaphragm and start the zone. When it loses the signal, the port closes and the zone shuts off. If the solenoid fails, the valve can't open — or sometimes won't close.
Symptoms of a bad solenoid
- Zone won't turn on even though the controller is sending a signal.
- Zone won't turn off if the solenoid sticks open.
- Buzzing or clicking at the valve.
- The zone runs only when the solenoid is manually opened.
Testing the solenoid
You can often confirm a valve works by manually opening it — loosen the solenoid a quarter turn until water flows. If the zone runs manually but not from the controller, the problem is the solenoid or the wiring to it. A multimeter can check the solenoid's resistance to confirm it's failed.
Replacing it
Replacing a solenoid is simple and inexpensive: shut off the water, unscrew the old solenoid from the valve, screw in the new one, and reconnect the two wires with waterproof connectors. This is far cheaper than replacing the whole valve.
When to call a pro
If a new solenoid doesn't fix it, the issue may be wiring or the controller. Our irrigation team can trace and resolve it.
Frequently asked questions
How do I know if my sprinkler solenoid is bad?
If a zone won't run from the controller but works when you manually open the solenoid, the solenoid or its wiring is likely the problem.
Is replacing a solenoid expensive?
No — solenoids are inexpensive parts and quick to swap, much cheaper than replacing the entire valve.
Arbol Roble has cared for Inland Empire landscapes since 1997, serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona and Riverside. Request a free quote or browse our residential and commercial services.
About the Author
The Arbol Roble team are licensed landscaping and irrigation professionals (CSLB License #1077455) serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona, Riverside, and the greater Inland Empire.