I often get questions about what it means when the timer says Opn or Open.  This message comes from the term ‘open circuit’ which means that the timer tried to turn on a valve, but the circuit was open, meaning a wire is disconnected, broken, or the solenoid is broken.

Typically this problem is caused by loose wiring or a bad solenoid.  Examine the connections at the timer and at the valves, typically found in a ground box.

It could also be caused by a timer or a back terminal board problem.  If your wiring looks good, you can send the timer and back terminal board to us for repair. 

If you only have one valve indicating an Open condition, you can try swapping wires with another valve to confirm that it’s a valve or wiring condition.  E.g., if station/valve #1 works and #2 is currently saying Open, then swap wires for #1 and #2.   Then try to turn on the 1st and 2nd stations using the timer’s manual function.  If the first station works and the 2nd station displays the Open message, then the problem is likely with the timer or backboard, send it in for repair.   If however, you now see station 1 reporting an open message, then the wire connections or solenoid is bad.  Solenoids usually fail shorted instead of open, but either is possible.  You can check either with a

Check wiring and/or replace the solenoid using the information below.

1. Solenoids are usually easy to replace, just turn the water off, disconnect the wires, unscrew the solenoid and replace it.
2. You can get them from your local landscape supply store (E.g, SprinklerWorld, or other, but probably not HomeDepot or Lowes). They’re usually less than $20.
3. If you want to pick up the parts first, take a picture of the valve to the store with you. They’ll be able to tell from the picture what solenoid you need.
4. Just turn the water off, disconnect the wires, unscrew the old solenoid; then put the new one in, hook the wires back up, and turn the water back on.

For additional testing, you can follow some of the steps to test the transformer.  Start with Check #3 on this page.  If you’re able to operate the valve, you know the transformer, wiring, and valve are good.

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