I don't know if my sensor or my cell is bad. My troubleshooting points to the sensor being bad. Disconnecting the sensor connector from the front board and performing the three checks gives the correct readings. My "manual" says that the front board is OK, but the sensor is bad. Also, the Aquapure pool temp reads 44 when the pool thermometer is at 81. Is it possible to buy the sensor and cell separately, so I can replace the sensor first and then the cell after, if the sensor doesn't solve the problem.