How to Troubleshoot a Solenoid Water Valve

Clear the small hole in the valve bonnet with a paper clip.
Clear the small hole in the valve bonnet with a paper clip. (Image: Gold paper clip image by Tomislav from

When you need to irrigate plants, for instance, a solenoid water valve turns the water on and off. This coil of electrical wire receives an electrical current from the irrigation controller, creating a magnetic force that pulls a metal plunger up inside of the valve. As the plunger rises, water pours from above the diaphragm, and then falls to a lower pressure area. The solenoid water valve opens since the force above the diaphragm has lessened and closes when the controller stops sending an electrical current. Troubleshooting a solenoid water valve helps you save time and keeps your irrigation valves operational for years to come.

Things You'll Need

  • Volt-ohm meter
  • Paper clip
  • Small piece of wire (optional)

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Open the solenoid water valve manually if the valve will not open by performing an external or internal manual bleed. Locate the solenoid lever on the solenoid. Turn on the lever and then turn the external manual-bleed screw or the internal manual bleed. Look for water flow.

Test the solenoid valve with a volt-ohm meter if the solenoid valve appears not to be receiving an electrical signal. Manually turn on the station you want to troubleshoot from the irrigation controller, and then read the voltage between the controller station terminal and the ground. Make certain you read 24 volts AC on your volt-ohm meter; otherwise, you may have a blown fuse either in the controller's transformer or in the irrigation controller itself.

Turn off the water and unscrew the solenoid from the valve bonnet if you still suspect a faulty solenoid. Place the small spring and plunger in a safe location where you will not lose them. These items help to force the solenoid plunger in a downward position. Inspect the solenoid plunger to ensure it does not have debris. Check the water valve's operation by turning on the valve manually from the irrigation controller. You know you have a working solenoid valve if the solenoid plunger pulls into the solenoid body. Examine the small hole in the valve bonnet by carefully using a small piece of wire or a paper clip to clear it, making certain you do not enlarge the hole. Water passes through this hole to the valve's downstream side, and this hole controls the valve's opening and closing speed. Turn off the valve and replace the small spring and plunger. Screw the solenoid onto the valve bonnet.

Tips & Warnings

  • To clean the solenoid water valve of algae and debris buildup, turn off the water and remove the valve bonnet and filter screens below the solenoid using a coin or a small screwdriver. Remove the debris by flushing the screens with water.


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