Check your water flow first.

The pressure switch is telling you there isn’t enough water moving through the heater. That’s a safety feature, not a glitch. So don’t try to bypass it—fix the flow.

Start with the easy stuff: clean your filter, make sure the pump is running at full speed (no timers messing with it), and check for air in the system (bubbles at the pump basket = air leak on the suction side). If you’ve got a variable-speed pump, bump it up to a higher RPM. If that doesn’t work, look for a clogged impeller, closed valve, or a sagging pool cover blocking the skimmer.

If none of that works, the switch itself could be bad—they do fail. But that’s the last thing to check, not the first. Replace it only after confirming water flow is strong and steady.

Nine times out of ten, it’s a dirty filter or low pump speed. Start there.