Error-code hub
Della indoor units display the code on the head's own readout, and the same code set runs across the Optima, Serena, Vario, Umbra, Motto and Econo lines - so a code from one line usually means the same thing on another. The 59 codes below come from Della's published manuals. Della shares its control platform with several value brands, so the E- and F- families will look familiar if you have owned one.
Unit applicability
This table is sourced for Econo Series. If your unit is a different generation or product line not named here, the same display code may vary by generation.
Common codes first
Ranking basis: we do not have failure-frequency telemetry. These are ordered by breadth of affected systems in the SplitAtlas catalog - the documented product line's published model count, whether the same code appears on more than one product line, and any manual applicability notes we hold. This is a breadth ranking, not a popularity claim.
bc means pm2.5 sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
bf means tvoc sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
bj means humidity sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
d4 means water full protect. In plain English, the unit is detecting a condensate drain or full-water protection condition.
d5 means access control protection. In plain English, an access-control or external protection input is preventing normal operation.
E0 means idu & odu communication failure. In plain English, the indoor and outdoor controls are not exchanging the expected signal, so the system may stop because the two halves cannot coordinate safely.
Safe first checks
These codes have homeowner-safe steps such as filters, airflow, condensate/drain checks, remote/controller items, or a single safe power reset. If the code returns, stop at the boundary in the card.
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Do not open covers, unplug sensors, or spray cleaner into the sensor area.
Read the full code guideTurn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Do not open covers, unplug sensors, or spray cleaner into the sensor area.
Read the full code guideTurn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Do not open covers, unplug sensors, or spray cleaner into the sensor area.
Read the full code guideTurn the system off if water is visible. Check only the outside drain outlet for an obvious clog or kink; do not open the indoor unit. Reset once only if dry and safe.
Read the full code guideUse the Della catalog to connect these manual error codes to current model pages and replacement options.
Econo Series
Econo Series
Econo Series
Econo Series
Econo Series
Optima Series
CL is the filter-duty reminder. It is a maintenance reminder to check and clean the user-removable indoor filter, not a hardware failure by itself.
bc means pm2.5 sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
bf means tvoc sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
bj means humidity sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
d4 means water full protect. In plain English, the unit is detecting a condensate drain or full-water protection condition.
d5 means access control protection. In plain English, an access-control or external protection input is preventing normal operation.
E0 means idu & odu communication failure. In plain English, the indoor and outdoor controls are not exchanging the expected signal, so the system may stop because the two halves cannot coordinate safely.
E1 means idu room temperature sensor failure (idu rt failure). In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
E2 means idu coil temperature sensor failure (idu ipt failure). In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
E3 means odu coil temperature sensor failure (opt). In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
E4 means ac cooling system abnormal. In plain English, the unit is detecting abnormal refrigerant flow, low refrigerant, or a cooling-system condition.
E5 means idu/odu mismatched failure. In plain English, the indoor and outdoor units do not match the way the controls expect.
E6 means idu pg fan motor / dc fan motor works abnormal. In plain English, a fan is not moving at the speed the control expects, so the system may stop to protect the coil, compressor, or inverter electronics.
E7 means odu ambient temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
E8 means odu discharge temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
E9 means ipm / compressor driving control abnormal. In plain English, the compressor drive is reporting abnormal feedback or load.
EA means odu current test circuit failure. In plain English, the outdoor unit detected voltage or current outside the safe operating range.
Eb means communication abnormal of main pcb and display board. In plain English, the indoor display board and main board are not communicating normally.
EC means odu modules communication failure. In plain English, outdoor electronic modules are not communicating normally.
EE means odu eeprom failure. In plain English, a control board, EEPROM, or board sensing circuit is not reading internal data correctly.
EF means odu dc fan motor failure. In plain English, a fan is not moving at the speed the control expects, so the system may stop to protect the coil, compressor, or inverter electronics.
EH means odu suction temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
Ej means odu central coil temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
En means odu gas pipe temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
EP means odu compressor casing top failure. In plain English, the outdoor inverter, IPM module, or compressor drive circuit is reporting abnormal load or protection.
EU means odu voltage test circuit abnormal. In plain English, the outdoor unit detected voltage or current outside the safe operating range.
Ey means odu liquid pipe temperature sensor failure. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
F0 means infrared customer-feeling test sensor failure. In plain English, the infrared or customer-feeling temperature sensing feature is not reporting normally.
F1 means electric power test module failure. In plain English, the outdoor unit detected voltage or current outside the safe operating range.
F2 means discharge temperature sensor failure protection. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
F3 means odu coil temperature failure protection. In plain English, the named temperature or air-quality sensor is not sending a believable reading, so the control cannot trust that part of the system.
F4 means cooling system gas flow abnormal protection. In plain English, the unit is detecting abnormal refrigerant flow, low refrigerant, or a cooling-system condition.
F5 means pfc protection. In plain English, the outdoor inverter, IPM module, or compressor drive circuit is reporting abnormal load or protection.
F6 means compressor lack of phase / anti-phase protection. In plain English, the compressor drive is reporting abnormal feedback or load.
F7 means ipm module temperature protection. In plain English, the system is protecting itself because a coil, compressor discharge line, or power module temperature is outside the expected range.
F8 means 4-way valve reversing abnormal. In plain English, the reversing valve did not switch refrigerant flow as expected.
F9 means module temperature test circuit failure. In plain English, a control board, EEPROM, or board sensing circuit is not reading internal data correctly.
FA means compressor phase-current test circuit failure. In plain English, a control board, EEPROM, or board sensing circuit is not reading internal data correctly.
Fb means limiting/reducing frequency for overload protection on cooling/heating mode. In plain English, the system is reducing compressor speed because a protection limit is being reached.
FC means limiting/reducing frequency for high power consumption protection. In plain English, the system is reducing compressor speed because a protection limit is being reached.
Fd means communication of the refrigerant sensor is abnormal. In plain English, the refrigerant detector is not communicating or responding normally.
FE means limiting/reducing frequency for module current protection. In plain English, the system is reducing compressor speed because a protection limit is being reached.
FF means limiting/reducing frequency for module temperature protection. In plain English, the system is reducing compressor speed because a protection limit is being reached.
FH means limiting/reducing frequency for compressor driving protection. In plain English, the system is reducing compressor speed because a protection limit is being reached.
FP means limiting/reducing frequency for anti-condensation protection. In plain English, the unit is reducing output to prevent condensation.
FU means limiting/reducing frequency for anti-frost protection. In plain English, the unit is protecting against an indoor-coil freezing or sub-cooling condition.
Fy means gas leakage protection. In plain English, the unit or detector is reporting refrigerant leakage or gas leakage protection.
H1 means high pressure switch malfunction. In plain English, a high- or low-pressure protection circuit is not normal.
H2 means low pressure switch malfunction. In plain English, a high- or low-pressure protection circuit is not normal.
Hd means refrigerant leak protection. In plain English, the unit or detector is reporting refrigerant leakage or gas leakage protection.
P0 means ipm module protection. In plain English, the outdoor inverter, IPM module, or compressor drive circuit is reporting abnormal load or protection.
P1 means over / under voltage protection. In plain English, the outdoor unit detected voltage or current outside the safe operating range.
P2 means over current protection. In plain English, the outdoor unit detected voltage or current outside the safe operating range.
P4 means odu discharge pipe over-temperature protection. In plain English, the system is protecting itself because a coil, compressor discharge line, or power module temperature is outside the expected range.
P5 means sub-cooling protection on cooling mode. In plain English, the unit is protecting against an indoor-coil freezing or sub-cooling condition.
P6 means overheating protection on cooling mode. In plain English, the system is protecting itself because a coil, compressor discharge line, or power module temperature is outside the expected range.
P7 means overheating protection on heating mode. In plain English, the system is protecting itself because a coil, compressor discharge line, or power module temperature is outside the expected range.
P8 means outdoor over-temperature/under-temperature protection. In plain English, outdoor temperature is outside the range the unit allows, or the outdoor unit is reading it that way.
P9 means compressor driving protection (load abnormal). In plain English, the compressor drive is reporting abnormal feedback or load.
PA means communication failure/mode conflict. In plain English, connected controls are asking for incompatible operation, or the unit is seeing a communication/mode conflict.