Sprinkler System Diagnostic in Solano, Napa & Sonoma County
A sprinkler diagnostic follows the path a zone’s signal and water take: controller, field wire, valve, pipe, heads, then the pressure behind them all. Each test clears one part before the next, so the fault is found by elimination. You get what we found, zone by zone, and a free quote for the fixes, in writing.
What does a sprinkler diagnostic test, and in what order?
Everything one zone depends on, in order. The controller sends power down a buried wire to the zone’s valve; the valve opens, and water fills the pipe beyond it and lifts the heads. A fault anywhere on that path looks the same from the lawn.
A drawing of one zone. Power runs from the controller down a field wire to the solenoid on the valve. Water runs along the main line from the supply to the valve, past a pressure gauge, then down the lateral to three heads. Test points TP1 to TP6 mark the controller, the field wire, the valve, the lateral, the heads and the pressure.
TP1Controller
The program, the rain sensor, the fuse and the power going out to the valves.
A program missing its start time, run time or days runs nothing. A blown fuse points to a short in the field wire, so TP2 comes next.
TP2Field wire
A meter reading down each zone’s wire, taken at the controller.
A reading too low means a short. Too high means a break: a cut wire or a failed splice.
TP3Valve: solenoid and diaphragm
The manual bleed. Opened by hand, the valve should run the zone; closed, it should seal.
Runs by hand but not from the controller: the fault is electrical. Won’t open or shut either way: the diaphragm, a plugged port, or grit on the seat.
TP4Lateral
The zone running, walked end to end.
A break on that zone alone: a soft wet patch, a weak far end, heads that barely lift.
TP5Heads
Every head on the zone: height, tilt, arc, nozzle, and the seal round the stem.
Sunk or tilted heads, water on the walk or the wall, a clogged nozzle’s broken pattern, a stem leaking from grit in its seal.
TP6Pressure
The water pressure with everything off, then again with the zone running.
Too high, and spray heads mist and fog instead of watering. Pressure-regulating spray heads fix it.
One zone, drawn for this page, not a client’s system.
This is exactly why an irrigation system should be properly inspected…
Is the fault in the wiring or the water?
Two tests split the system in half. First, the valve’s manual bleed: if the valve runs the zone by hand but not from the controller, the water side works and the fault is electrical.
Second, whether the ground is wet with everything off. The main line holds water under pressure all the time; a zone’s lateral, only while that zone runs. Wet with the system off points to the main line, or to a valve seeping into its zone, which shows as a puddle at the lowest head. Wet only while a zone runs points to that lateral or its heads.
A trickle from the lowest head right after a zone stops is the pipe draining; a seep keeps going. Leak detection & repair · Valve replacement
What do you get at the end?
A written list, zone by zone: what was found and the fix, with a free quote. Carlos walks you through it, and you decide what gets fixed and when.
Sometimes the professional recommendation isn’t the cheapest fix… it’s the fix you won’t have to call us back for.
| Zone | Found | Fix |
|---|---|---|
| 3 · Back lawn | A short at a taped splice in the valve box | New section of wire, splices in waterproof connectors |
| 1 · Front lawn | Two heads sunk below the grass; one spraying the walk | Raise both, re-aim the arc |
| 2 · Front beds | Puddle at the lowest head with the system off; grit on the diaphragm seat | Clean or replace the diaphragm |
| All spray zones | Spray heads misting | Pressure-regulating spray bodies |
…diagnosed and fixed a sprinkler issue we'd been dealing with
Andres Rodriguez, Google review, Feb 2026 (opens in a new tab)
Diagnosed one day and fixed the problem the next
Keith Brown, Google review, 2024–25 (opens in a new tab)
…he took detailed notes and included it all in a written estimate
Shahla Farahnak, Google review, May 2026 (opens in a new tab)
In Fairfield: Sprinkler repair in FairfieldOne zone out: One sprinkler zone not workingThe whole system: Irrigation
Won’t shut off, or a jump in the bill
The valve isn’t sealing, or still has power.
Grit on the diaphragm seat, a plugged diaphragm filter, a stuck solenoid plunger or a manual bleed left open will each keep a valve running. So will a controller that is still sending power. If you know where the irrigation shut-off is, close it, then call.
Yes, when a pipe or head leaks.
A 1/32-inch leak in a cracked pipe wastes about 6,300 gallons a month, and it can do that without showing in the lawn. Town rules apply too: Vallejo wants leaks stopped within 36 hours of finding them; Napa wants leaks of more than a gallon a minute fixed within 30 days of finding them; Windsor counts a leak left running too long as water waste. Checked Sep 2026. A diagnostic either finds the leak or rules the sprinklers out.
VallejoNapaWindsorLeak detection & repairWatering rules by city
First, find the fault.
Carlos runs every zone, then puts what he finds and a free quote for the fixes in writing.
Call for a free quote(707) 329-8391
