Catalina Spa With Balboa Controls OH Error

[rhinotech]

My spa keeps displaying the OH error. I have changes the Temp and High limit sensors and I have ran it with out the filter. I was wondering what else it could be. I have also replaced the Heater as it did not work.

[MaryH]

If you have good water flow going through the heater from the pump and both sensors are new it may be the circuit board causing it.