Clogged nozzles on sprinkler heads. From
time to time, retracting sprinkler head nozzles become clogged with
dirt or other debris. You should periodically inspect the operation of
your system to ensure the proper function of all nozzles.
Sprinkler zones that do not turn off properly.
Either a malfunctioning timer or a stuck valve usually causes this
problem. Try unplugging the electricity to the timer. If the sprinkler
goes off, the problem is most likely with the timer. If it stays on,
the problem is most likely a stuck valve.