Balboa · BP series (TP400, TP600, TP800, TP900, spaTouch panels)Fix soon

HTR MAY BE DRY on a Balboa hot tub: heater may be dry

The control thinks the heater may not have enough water in it. The spa shuts down for 15 minutes and then retests. Check the water level before using it.

Also shown as: M028, dr, The heater may be dry, WILL RETEST SHORTLY

Most likely causes

  1. 1Air lock after a drain and refillmost likely
  2. 2Low water levelmost likely
  3. 3Clogged filtercommon
  4. 4Pump not priming or not runningless common

What to try, in order

  1. Fill the tub to the normal level.
  2. Bleed the air lock: open all jets and pulse the jet pump between low and high for 10 to 15 seconds at a time.
  3. Turn off power at the breaker and rinse the filter.
  4. Restore power and press any button to reset, or wait for the automatic retest.
  5. If the message keeps returning, leave the tub off and have the pump checked.

HTR MAY BE DRY questions

What does M028 mean on my spa?

M028 means the heater may be dry. It is a warning with an automatic retest after 15 minutes.

Why does this show after I fill the tub?

Trapped air stops water from reaching the heater. Refill through the filter compartment next time to push air out as the tub fills.

Related codes

Balboa -- · Temperature not yet knownBalboa CHEK PH · Maintenance reminderBalboa CLN FLTR · Filter reminderBalboa CNFG FAIL · Configuration errorBalboa dr · Heater may be dryBalboa dry · Heater is dryBalboa Ecn · Economy modeBalboa FLO · Low water flow

General guidance. Follow your manufacturer's instructions; anything inside the control box is work for a licensed professional. Updated October 5, 2026.