‘Err’ will be displayed for a few seconds then the display will show the previous reading. Successful pH calibration indicators will disappear. The Bluelab Combo Meter is in an uncalibrated state, therefore recalibration is required.

Possible causes for an ‘Err’ message:
  • Calibration solutions contaminated
  • Wrong solutions used
  • pH probe contaminated
  • pH probe not properly attached
  • pH probe worn out or damaged
  • Calibrate to pH 7.0 FIRST then to pH 4.0/10.0


This is intended as a self-help general troubleshooting guide. Please contact us if you need specific help.


Thank you and happy growing!