A few weeks ago we turned on our spa and heard a loud pop noise. We inspected the heater to find that the blower had "blown up." We replaced the blower but the heater will not ignite. We reset the system by turning off the power...still nothing. The display shows the SW Pressure and Thermostat are on, but the heater light does not come on. We do not smell gas, and the blower runs fine. The system then shows the E04 error code for ignition failure.

Any thoughts?

Sounds like to pressure switch on the blower is not completing the ignition circuit. There should be a rubber tube somwere on the blower assembley leading to a pressure switch with two wires on it. You can test the switch by removing the wires and connecting them together and see if it will light. If the blower did indead blow up like you say, it could have damaged the diaphragm in the pressure swith. The pressure switch light on the display is for the water pressure switch letting you know you have enough flow through the heater.

Welcome to TFP!!

Any noise when it tries to fire?

I think Jeff has the right spin on this, but wanted to check.

Thank you so much for the advice. It worked!!:) We ran a jumper wire to bypass the pressure switch and the heater fired up. Thanks again for the advice. We will order a new pressure switch and be as good as new.