Sprinkler System Troubleshooting: Symptom-First Checks for Zones, Valves and Heads

If no sprinkler zones run, first verify the master water supply and any rain sensor shutoff before checking individual valves. If only one zone fails, diagnose that station, its wiring and solenoid, and valve and head condition - shutting off power and water before opening a valve and treating voltage and resistance specs as model-specific.

Sprinkler troubleshooting: no zones vs. one failed zone

Triage before you open components. The symptom pattern determines the next check.

• If no zones run, first verify the master water supply is on and any rain-sensor or other shut-off device is not interrupting operation before diagnosing individual valves.

• If only some zones fail while others work, the controller is less likely to be the system-wide cause. Focus diagnosis on the failed stations individually rather than replacing system-wide components.

Electrical checks: Rain Bird guide values only

Electrical values vary by manufacturer and model. Do not treat the numbers below as universal specifications. Always confirm requirements in your own controller and valve manual and treat voltage, resistance, and solenoid specifications as model-specific unless confirmed in your documentation.

• For the Rain Bird diagnostic setup, station output of 24–28 VAC is treated as in range. In that setup, resistance testing is performed with the controller off.

• The Rain Bird guide lists 20–60 ohms as its normal station-resistance range. Readings above 60 ohms point to an open solenoid, a broken or nicked wire, a splice issue, or a bad connection at that station.

Safety note: Hard-wired controller power work may require an electrician. De-energize the controller as directed by the manual before resistance testing or disconnecting station wiring.

Valves that won't open or stay on: safe inspection

Use a safe sequence and isolate utilities before opening a valve. Do not open a pressurized valve; opening a pressurized valve can cause injury.

• A valve that will not open can be caused by a damaged or debris-clogged opening mechanism. After shutting off water, inspect and clean bleed ports and the diaphragm, replacing a damaged diaphragm.

• For a valve that stays on, first try turning the controller off. If flow continues, shut off the irrigation main before opening the valve for inspection.

• A continuously running or weeping valve may result from debris at the diaphragm or seat, a torn diaphragm, a manually opened solenoid, or an open bleed screw. Inspect the exact valve model’s components before replacing parts to confirm the cause.

Safety note: De-energize and isolate water before opening a valve or removing a solenoid.

Low-head drainage vs. valve leak

Water that temporarily drains from the lowest sprinkler after a zone stops can be normal low-head drainage as water in the line drains to the lowest point, rather than indicating a valve failure. If wetness persists continuously, or water never stops, check for a valve that is not fully closing and for leaks at the valve.

Heads, pressure, and seasonal flush

Inspect zone by zone with water on:

• Operate one zone at a time to inspect for clogged, misaligned, tilted, buried, or broken heads and for damaged or missing nozzles.

• Fine misting and leaks at sprinkler heads can indicate excessive pressure. Pressure regulation may be a corrective option, but sizing and suitability are system-specific to your zone and components.

• At seasonal startup, flush each zone by removing the last head or nozzle or drip end cap, then run water briefly before reinstalling it. The checklist specifies this flush as 1–2 minutes.

Inspection schedule

For ongoing maintenance, inspect the system each spring and at least monthly during the growing season. Preseason checks include controller wiring, sensor connections, and time and day settings, along with the head and valve checks above.

Related guides

See related troubleshooting guides for sprinkler controllers, valves, and heads when symptom-first checks do not resolve the issue.