Most likely the filter pump or other part of the motor base needs to be serviced for an E90 error. Before addressing the repair, make sure the problem is not caused by water quality (especially high calcium) or a clogged cartridge - try replacing it. If the problem persists, check the condition of the pump: unscrew the cartridge from the inlet and start the pump. If the filter pump is running, the problem is elsewhere. If it does not work, the pump must be checked and repaired. Warranty repairs are carried out by your dealer; claim the spa from your dealer. For out-of-warranty repairs, you can contact us on our online form for spare parts or contact our service center.