Sprinkler Troubleshooting

Yard Smarts guide

Work out what is wrong before you pay somebody to find out

A lot of irrigation call-outs are diagnosis, and diagnosis is billable. Ten minutes with this page will often tell you what is actually wrong — and sometimes that it is something you can fix yourself in the time it takes to read about it.

Where it is not, you will at least be able to say “zone four will not shut off and I can hear the valve buzzing” instead of “the sprinklers are broken”. That single sentence can be the difference between one visit and two.

Before anything else: find your irrigation shut-off valve.

It is usually in a ground box near the water main or the backflow preventer. Knowing where it is turns a stuck valve from a flooded yard and a large bill into a minor annoyance. Go and find it now, while nothing is wrong.

Irrigation valve and pipework in a ground box

Start here

Three checks that solve a surprising share of calls

Is the rain sensor stuck?

A sensor that has swollen shut or failed will hold the whole system off indefinitely, and the controller will look completely normal while it does. Check it before you check anything else.

Has somebody moved the switch?

Controllers have an off / auto / manual selector, and a separate sensor bypass. Both get knocked, and both produce a system that appears dead for no reason.

Is the main shut-off fully open?

After any plumbing work, or a winterization done by somebody else, the irrigation shut-off is often left partly closed. It shows up as weak pressure across every zone at once.

Symptom

One zone will not come on

Everything else runs, but one zone does nothing.

Start the zone manually at the controller. If you hear a faint click at the valve box, the controller and wiring are probably fine and the valve is the suspect.
Check the valve's flow control and bleed screw — somebody working in the yard may have closed it.
Look for a chewed or corroded wire splice in the valve box. Wet splices are the single most common cause of a dead zone on an older system.

A solenoid tester tells you in seconds whether the coil is drawing current. Without one you are replacing parts on a guess.

Symptom

A zone will not shut off

Water keeps running after the program ends, or the zone starts on its own.

Turn the system off at the controller. If the zone keeps running, the controller is not the problem — the valve is stuck open.
Close the main irrigation shut-off valve to stop the water while you sort it out. This is the emergency step and it is worth knowing where that valve is before you need it.
Debris under the diaphragm or a perished diaphragm are the usual causes.

This is the failure that costs real money. A stuck valve can run thousands of gallons before anyone notices, and it usually shows up on the bill rather than in the yard.

Symptom

Nothing runs at all / the controller is blank

No zones, no display, or a display showing an error.

Check the outlet and the breaker — controllers in a garage often share a circuit with something else that tripped.
Check the controller's own fuse and its transformer.
Look for a 'sensor' or 'rain' switch on the face of the controller set to the wrong position, and for a rain sensor that is stuck wet and holding the system off.

A rain sensor stuck in the tripped position is the cause often enough to be worth checking before anything else.

Symptom

Low pressure or weak spray on one zone

Heads barely lift, or the pattern falls short of where it used to.

Check whether a head is missing its nozzle or has been broken off — one open riser drops pressure across the whole zone.
Look for a wet or unusually green patch, which suggests a break in the lateral line feeding that zone.
Clean the filter screens under the nozzles. Grit is common after any mainline work in the street.

If every zone is weak rather than one, the problem is upstream — the main shut-off partly closed, a pressure regulator, or a mainline leak.

Symptom

One head will not pop up

The zone runs but a single head stays down or barely rises.

Clear soil and turf that has grown over the head. Clay heaves and buries heads season by season.
Check the filter screen under the nozzle for grit.
Look at whether the head has been driven over or struck — a cracked riser leaks pressure inside the housing.

Heads that repeatedly end up buried are usually set too low for how much this soil moves, and re-setting them to grade is a permanent fix rather than an annual chore.

Symptom

A head is spraying wildly or throwing a geyser

One head is fountaining, misting badly, or soaking a fence.

A geyser means the nozzle is gone or the head is broken off at the riser — shut the zone off and stop wasting water.
Fine misting usually means pressure is too high for the nozzle, which wastes a surprising amount to drift.
Overspray onto fences, brick and pavement is a nozzle and arc problem, and it stains and rots what it hits.

Pressure-regulated heads solve chronic misting properly. Turning the run time down does not.

Symptom

Water pooling in one spot every cycle

A patch stays soggy, or there is standing water after every run.

Check for a leaking head or a cracked fitting directly under the wet area.
Consider whether that zone is simply running longer than clay can absorb — try splitting the run into cycles before assuming a leak.
If it stays wet without the system running, it is drainage rather than irrigation.

Persistent soggy ground with the system off is a drainage problem, and no amount of controller adjustment will fix it.

Symptom

The bill jumped and nothing looks wrong

No visible geyser, no soggy patch, just a much larger bill.

Turn off everything in the house, read the water meter, wait two hours with nothing running, and read it again. Movement means a leak on your side of the meter.
Check whether the controller has two start times set — a duplicate programme quietly doubles everything.
Check that the seasonal adjust or water budget percentage has not been left at a summer setting.

A mainline leak underground can run for months with nothing visible on the surface. The meter test is the only reliable way to find it early.

Irrigation plan showing valve and zone layout

Know where the line is

What you can do, and what needs a licence

You are entitled to work on your own irrigation system at your own home. Cleaning a nozzle, clearing soil off a head, resetting a controller and swapping a broken spray head are all reasonable homeowner jobs.

Where it changes: under Texas Commission on Environmental Quality rules, anyone selling, designing, installing, altering, repairing or servicing an irrigation system for somebody else must hold a TCEQ licence. Anything touching the backflow prevention assembly or the connection to the water supply is firmly in that territory, because it protects the drinking water supply, not just your lawn.

So: fix your own heads happily. If somebody is charging you to do it, ask for their licence number. Ours is TCEQ Licensed Irrigator LI5654.

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Work out what is wrong before you pay somebody to find out

Three checks that solve a surprising share of calls

Is the rain sensor stuck?

Has somebody moved the switch?

Is the main shut-off fully open?

One zone will not come on

A zone will not shut off

Nothing runs at all / the controller is blank

Low pressure or weak spray on one zone

One head will not pop up

A head is spraying wildly or throwing a geyser

Water pooling in one spot every cycle

The bill jumped and nothing looks wrong

What you can do, and what needs a licence

Diagnosed it and would rather not do it yourself?

Related guides

Irrigation & Grass Basics

DFW Watering Guide

Winterization

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