The fundamental reason is water flow through the spa control system, if the water is not flowing at a rate to satisfy the pressure switch, it will result in one of the error codes above. These error codes are caused by a variety of reasons. These codes are related to flow issues or the pressure switch/flow switch and are by far the most common error codes.

Then you have to check if the flow of water is sufficient in the heater and to remove the air by unscrewing it.

Check if the valves and the jets are ok and if the filter is clean.Received from Monarch regarding err 6.Possible causes are an airlock in the system, lack of flow through the heater (could be caused by dirty filters, closed gate vales, or a faulty circ pump), a faulty sensor or a faulty pcb err 6 : Thermal Cut Out Tripped - This error means that the temperature sensor inside the heater has detected temperatures which could damage the heater as a result the heater will not switch on until until it has cooled to below 38°c and the system has been reset (turn off and on at the mains).err 3 : Stuck Button - Probable cause is faulty topside control.This includes Northern Ireland, Channel Islands and Scottish Islands. Any orders placed for chemicals that require shipment overseas will automatically be refunded. Shipments Outside UK Mainland: We can no longer ship chemicals outside UK Mainland.We are no longer able to serve you on the premises so all orders must now be placed online.

Please email our customer service team to arrange a collection date and time.

Order Collections: Orders must be placed online prior to arriving at our warehouse.

Leisure bay spa troubleshooting codes