Owner's manual
31115 V1  LTC4 
Page 37  Operating Manual 
www.grantinstruments.com 
Symptom 
Possible cause 
Action required 
Display shows 
“Low liquid 
Alarm” 
Liquid level has 
dropped below 
minimum level 
Check that the liquid level in the bath is 
adequate 
Display shows 
“Internal 
temperature 
probe Fault” 
Faulty temperature 
probe 
Have a competent person check the probe for 
an open or short circuit fault or contact Grant. 
Display shows 
“Internal/External 
Temp Diff Too 
Big” 
There is a 
temperature 
difference of more 
than 5 degrees 
between the internal 
and external probe 
Check the external probe is properly connected 
at the rear panel. 
Check the external probe is correctly positioned 
in the bath liquid and circulation is not 
restricted. 
If the external probe is not required, select the 
internal probe using the Settings menu 
Display shows 
“Overheating- 
Power reduced ” 
Heating water at or 
near to boiling 
without lid 
Heating very large 
volumes of liquid with 
large thermal losses 
Add a lid to reduce thermal losses and leave 
unit running with the “Overheating” warning 
present. If the alarm has not cleared within 1 
hour contact Grant. 
Add measures to reduce thermal losses and 
leave unit running with the “Overheating” 
warning present. If the alarm has not cleared 
within 1 hour contact Grant. 
Display shows 
“Service required 
01” 
Faulty fuse(s), relay 
or heater element 
Have a competent person check the product or 
contact Grant. 
Display shows 
“Service required 
02” 
Pump or propellor is 
obstructed 
Faulty motor 
Remove obstruction. 
Have a competent person check the product or 
contact Grant 
Display shows 
“Cross-check 
Failure” 
PCB fault 
Have a competent person check the product or 
contact Grant. 
For any other errors or service requests, please contact Grant Instruments service 
department. 










