contact the manufacture of the sensors and display.
sometimes the display is faulty and often the tank sensors go wacky...
the company has been pretty good about replacing sensors OR the display under warranty...
as i recall these bits are covered for 5 years.
replacing the display isn't difficult....
the tank sensors are easy to replace (screw in, plug in wire) AFTER gaining access to them.
IF MP is given the model/size stream, the display unit can be sent out PREcalibrated...
which seems like a great idea and time saver, IF the calibration works.
the PRE settings didn't help in my unit, so i still had to run through the REcal' process.