| Problem | Possible cause | Remedy |
|---|---|---|
| Analog output reading is unchanging and appears incorrect. | Analog output is in error state. | Remove the cause of the error state and the analog output will recover its normal function. |
| Probe outputs stars "****" on serial line instead of measurement data. | Incorrect supply voltage. | Check the power supply. Check the active errors using the ERRS command on the serial line. |
| Unsuitable operating environment. | Verify that the operating environment is within specified operating limits. | |
| Unable to access probe on the RS-485 line. | Incorrect wiring. | Check that the RS-485 connection is wired correctly. |
| Probe in POLL mode with unknown address. | Power cycle or reset the probe and try again. | |
| CO2 measurement not working. | Condensation on the sensor. | Remove the filter and check if condensation has formed on the sensor. If yes, dry out the condensation with instrument air and insert a new dry filter. Keep the probe powered and operating to prevent re-occurrence. |