There are 2 x controllers depending on year purchased, the Carel ECO controller and Danfoss ECO controller, they both have basic error codes.

CAREL (All prior to Mid 2017)
“E0” cabinet probe/sensor fault.
Part number GSP3-SENSOR-CABINET, price $49.00

“E1” evaporator probe/sensor fault
Part number GSP3-SENSOR-EVAPORATOR, price $49.00

“dF” alternate flash with cabinet probe/sensor temperature whilst in defrost

“dor" door open timeout. Turn unit off and on, *this should not show on later models as this function has been disabled
**Click here to Download Instructions;
GSP - HOW TO CLEAR DOR ERROR.pdf

“E3” refrigerant system failure alarm can be many things from faulty fan to loss of gas.
Check inner fan is running, Part number GSP3-FAN-INNER, price $119.00
Check rear fan is running, Part number GSP3-FAN-UNDER, price $169.00

“EnS“ alternating to cabinet probe temp, unit is in "Energy Saving Mode".
To take out of energy saving mode press and hold the 'ES ' button for 5 seconds.

The Danfoss codes are at this link (Late 2017 Onwards);
GSP-NEW-DANFOSS-ERROR-CODES-2018.pdf