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

SNSR SYNC on a Balboa hot tub: sensor sync fault

The two heater sensors have been out of sync for at least an hour, and the spa has shut down. It needs service before it will run normally again.

Also shown as: M026, SNSR SYNC CALL FOR SRVC, Sensors are out of sync - call for service

Most likely causes

  1. 1Failed or drifting temperature sensormost likely
  2. 2Corroded sensor connection at the boardcommon
  3. 3Persistent poor flow through the heatercommon
  4. 4Circuit board faultless common

What to try, in order

  1. Reset power at the breaker for 30 seconds to see if the fault clears.
  2. With power off, clean the filter and confirm the water level.
  3. Note the control pack model from its label so the right sensors can be ordered.
  4. If the fault returns, schedule a technician.

SNSR SYNC questions

What does M026 mean?

M026 is the fault version of the sensor sync warning. The sensors have disagreed for an hour or more, so the system shuts down.

Is this an expensive repair?

Usually not. Sensors are among the cheaper spa parts. The cost goes up only if the circuit board turns out to be the cause.

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.