7-7 
 
7.2.4 Troubleshooting 
When the sampling system of the CO
2
 module works abnormally, check if the sampling line 
is kinked. If not, remove the sampling line from the water trap. Then, if a prompt message 
indicating airway malfunction appears on the screen, it means that the water trap is occluded. 
In this case, you must replace the water trap. If no such prompt message is displayed, it 
means that the sampling line is occluded. Then you must replace the sampling line. 
 
7.2.5 Zero the Sensor 
Zeroing the sensor aims to eliminate the effect of baseline drift on the readings during the 
measurement, so as to ensure measurement accuracy. 
 
For CO
2
 module, a zero calibration is carried out automatically if necessary. You can also 
start a manual zero calibration when it is necessary. To manually start a zero calibration, 
select the [Setup] key→[Maintain]→[User]→enter the required password→[CO
2
 In 
Maintenance]. Then select [Zero]. Do not need to disconnect the sensor from the breathing 
system when performing the zeroing. 
 
7.2.6 Calibrate the Sensor 
For a sidestream CO
2
 module, a calibration should be performed once a year or when the 
measured value has a great deviation. For details, refer to12 Maintenance .