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8009441/YN36/V3-0/2015-08| SICKOPERATING INSTRUCTIONS|GM35
Subject to change without notice
TROUBLESHOOTING AND CLEARING MALFUNCTIONS 
9.3.3 Warning messages for the GM35 SR-unit
Warning message Component/possible causes Clearance
Air purge low SLV Volume flow is below the set 
threshold.
▸ Check purge air supply (blower, hoses), 
exchange filter on purge air blower when 
necessary, 
see “Checking and replacing the 
purge air filter”, page 95.
Chopper freq. Chopper disk frequency outside 
tolerance.
▸ Exchange lamp module; contact Service.
CD: Filter watch SLV Low-pressure monitor of purge air unit 
switches on binary input.
▸ Check purge air supply (blower, hoses), 
exchange filter on purge air blower when 
necessary, 
see “Checking and replacing the 
purge air filter”, page 95.
CD: P No Signal SLV No signal from pressure sensor.
▸ Check connection and cable connection of 
pressure sensor on purge air fixture and repair 
if necessary.
CD: P out of range SLV Sample gas pressure < 500 or > 
1200 hPa/mbar.
▸ Check resp. replace pressure sensor.
CD: T Air Sign. SLV Broken sensor resp. no temperature 
sensor (purge air temperature) 
connected.
▸ Check connection and cable connection of 
temperature sensor (purge air temperature) on 
purge air fixture and repair if necessary.
CD: [t] No Signal SLV Broken sensor resp. no temperature 
sensor (exhaust gas temperature) 
connected.
▸ Check connection and cable connection of 
temperature sensor (exhaust gas temperature) 
on purge air fixture and repair if necessary.
CO/N
2
OLow sig. • CO(N
2
O) measuring channel 
contaminated.
• Dust content too high.
• IR source aged.
▸ Check contamination; clean optical interfaces 
(
see page 90f).
▸ Check optical alignment, 
page 92.
▸ Exchange IR source or contact Service.
CO/N
2
O not ready • CO (N
2
O) measurement not ready.
• Signal distorted.
• Warming up phase.
▸ Wait approx. 30 minutes until the operating 
temperature is reached.
▸ Contact Service if necessary.
CO2 Reference Deviation of control value 
measurement too high.
▸ Carry out zero adjust on GM35; 
see page 79.
▸ Perform maintenance, 
see “Maintenance”, 
page 88.
▸ Contact Service if necessary.
H2O Low sig. • H
2
O measuring duct contaminated.
• Dust content too high.
• IR source aged.
▸ Check contamination; clean optical interfaces 
(see page 90f).
▸ Check optical alignment, page 92.
▸ Exchange IR source or contact Service.
H2O not ready • CO
2
/H
2
O measurement not yet 
ready.
• Signal distorted.
• Warming up phase.
▸ Wait approx. 30 minutes until the operating 
temperature is reached.
▸ Contact Service if necessary.