Sprinkler Zone Won't Shut Off: Valve Fault, Not Controller

When one sprinkler section runs continuously despite the Rain Bird controller showing "off" and correct programming, the fault is in the zone valve, not the timer.

Why It's the Valve

• Controller sends 24VAC to open valve; 0V to close.
• If controller is off/unplugged and valve still runs, it's mechanically stuck open.
• Common causes: torn diaphragm, debris in valve seat, solenoid plunger stuck up.

Quick Fix

1. Locate the valve for the stuck zone (usually in ground box).
2. Try manual bleed screw—tighten fully clockwise.
3. If still running, shut off main water, disassemble valve.
4. Clean all parts, replace diaphragm (~$10), reassemble.
5. Or replace entire valve top (bonnet+diaphragm+solenoid) if available.

Don't replace the controller—it's doing its job. The valve is the mechanical component that fails.