pentair 400 touch pad doesn't work , spa light and service light on-heater wont start


New member
Dec 8, 2019
heath Texas
I replaced the touchpad ...same symptoms. I looked at the motherboard and see the sfs light is on. I am planning on replacing the stack flue sensor,(it looks fine) but I am skeptical as to how this will make the touchpad reactive. Right now spa light and service light illuminate but pushing any of the buttons has no effect. Any Ideas? BTW the heater is only a year old,,, no sign of rodents and everything looks brand new.

Pool Clown

In The Industry
Sep 5, 2008
Silicon Valley, CA
Spa light on means that thermostat is currently active.

Which service light? Service Heater? or Service System?

Service heater light means that the safety routine found an open or wonky circuit, SFS? and startup has stopped. Nothing will happen until that circuit is in normal range again (and power cycled). Now since this heater is relatively new, you dont have a stack flue switch, you have a stack flue sensor. It is probably giving an erroneous temperature (resistance) value, or it is open.

Service system light means that the heaters' pressure switch is open. This usually means that the filter is not on, or filter pump has lost prime, dirty filter, or maybe a valve is partially or fully closed.

Note: If the heater is only one year old, you may still be under Pentair warranty depending on where, how, or what you may have bought along with it.
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