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

HTR FLOW LOSS on a Balboa hot tub: heater flow reduced

There may not be enough water flowing through the heater to carry heat away, so the heater has paused. It restarts by itself after about a minute if flow returns. The tub is safe to use.

Also shown as: M016, HFL, HEATER FLOW IS REDUCED, The water flow is low

Most likely causes

  1. 1Dirty or clogged filtermost likely
  2. 2Low water levelcommon
  3. 3Air lock after a refillcommon
  4. 4Closed jets or partly closed valvesless common
  5. 5Weak pumpless common

What to try, in order

  1. Check that the water level is above the highest jets.
  2. Turn off power at the breaker, remove the filter, rinse it, and reinstall it.
  3. Open all jets and make sure suction covers are clear.
  4. If you recently refilled, bleed air by pulsing the pump between speeds for 10 to 15 seconds at a time.
  5. Restore power and watch for the message. If it returns, try a filter cleaner soak or a new filter.

HTR FLOW LOSS questions

What does M016 mean on a Balboa BP spa?

M016 is the message code for reduced heater flow, the same condition older systems show as HFL. A dirty filter is the usual cause.

Can I use the hot tub with HTR FLOW LOSS?

Yes. The heater is paused but the tub is otherwise working. Clean the filter soon so it does not escalate to HTR FLOW FAIL.

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.