Troubleshooting
Error
Problem
Solution
Ensure that batteries are
properly
installed with correct
polarity
Display
No display when pressing
power button
Press and hold power
button to retry
Replace batteries
Open the battery
compartment and
using a small metal tip,
press the
reset button
Display Readings frozen on display
Check to see if data hold
function is
activated. Press hold to
deactivate.
Display Slow Response
Check for air flow
blockage to
sensors
E01/E33 CO
2
sensor is not working
Replace the battery
E02
Measurement is below the
range of the meter
Check readings in a
different area
E03
Measurement is above the
range of the meter
Check readings in a
different area
E04
Data error
Contact Extech for
service
E11
Humidity calibration Error
Retry humidity
calibration
E16
CO calibration error
Contact Extech for
service