"Sensor A" (SnA or SA) is Not Operating Correctly.
The Sensor Connected to the "Sens.A" Connector on the System Board may have failed and Spa Functions are Disabled. Contact your Dealer or Service Organization.
A Sensor Failure Message may indicate Excessively High Heater Temperatures which can Scald or Burn!
If the Heater is Not Cool Enough to Safely Service, allow the Heater to Cool before Testing.
For all Diagnostic Messages, click on below link.