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 you’re wiring looks good, you can send the timer and back terminal board to us for repair.
You can test the valves and wiring ahead of time by following 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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