Mitsubishi Ecodan & Daikin Altherma Fault Codes / Error Codes
Below are some common fault codes for Mitsubishi Ecodan and Daikin Altherma air to water heat pumps.
IMPORTANT: These codes have been supplied for your information, however we recommend that all maintenance of heat pump units should be carried out by a suitably qualified F-Gas engineer. Failure to comply may result in serious harm or fatality.
Call us on 01242 821438 to book an engineer visit.
Mitsubishi Ecodan heat pump error codes / fault codes
Applicable model numbers: PUHZ-W50VHA, PUHZ-W85VHA2, PUHZ-W112VHA2, PUHZ-HW140VHA2, PUHZ-HW140YHA2, PUHZ-SW40VHA, PUHZ-SW75VHA, PUHZ-SW120VHA
| Error Code | Description |
|---|---|
| F3 | Low pressure switch failure |
| F5 | High pressure switch failure |
| F9 | Both pressure switch contacts are open at the same time |
| EA | Mis-wiring fault between FTC and Ecodan |
| EB | Mis-wiring fault between FTC and Ecodan |
| EC | Unit cannot finish start up process |
| U1 | Ecodan high pressure fault |
| U2 | Ecodan high compressor discharge temperature |
| U3 | Ecodan discharge thermistor problem |
| U4 | Open or close circuit Ecodan thermistors |
| U5 | Inverter heat sink overheat protection |
| U6 | Inverter/Compressor over current |
| U8 | Ecodan fan motor problem |
| U9 | Over voltage or under voltage |
| UD | Overheat protection |
| UF | Compressor over current/Compressor lock |
| UH | Abnormal running current |
| UL | Open circuit |
| UP | Over current |
| E0 | Transmitting Error |
| E1 | Faulty controller |
| E3 | Transmitting Error |
| E4 | Receiving Error |
| E5 | Receiving Error |
| E6 | Indoor/Outdoor communication error |
| E8 | Indoor/Outdoor communication error |
| E9 | Indoor/Outdoor communication error |
| EF | Non-defined error code - noise interference |
| ED | Serial communication fault between Ecodan main board and Ecodan inverter board |
| P1 | Flow temp sensor fault |
| P6 | Over heating at heat exchanger |
| P8 | No temp change at plate heat exchanger |
| P9 | TH5 Fault |
| PE | Inlet water temp fault |
Daikin Altherma heat pump error codes / fault codes
Applicable model numbers: ERLQ004CAV3, ERLQ006CAV3, ERLQ008CAV3, ERLQ011CAV3, ERLQ014CAV3, ERLQ016CAV3, ERLQ004CBV3, ERLQ006CBV3, ERLQ008CBV3, ERLQ011CBV3, ERLQ014CBV3, ERLQ016CBV3, ERHQ004BAV3, ERHQ006BAV3, ERHQ008BAV3, ERHQ011BAV3, ERHQ014BAV3, ERHQ016BAV3, EBHQ004BAV3, EBHQ006BAV3, EBHQ008BAV3, EBHQ011BAV3, EBHQ014BAV3, EBHQ016BAV3, ERHQ004BBV3, ERHQ006BBV3, ERHQ008BBV3, ERHQ011BBV3, ERHQ014BBV3, ERHQ016BBV3, ERHQ004BCV3, ERHQ006BCV3, ERHQ008BCV3, ERHQ011BCV3, ERHQ014BCV3, ERHQ016BCV3, ERHQ004AAV3, ERHQ006AAV3, ERHQ008AAV3, ERHQ011AAV3, ERHQ014AAV3, ERHQ016AAV3, ERHQ004ABV3, ERHQ006ABV3, ERHQ008ABV3, ERHQ011ABV3, ERHQ014ABV3, ERHQ016ABV3, ERHQ004ACV3, ERHQ006ACV3, ERHQ008ACV3, ERHQ011ACV3, ERHQ014ACV3, ERHQ016ACV3, RLQ011CW1, ERLQ014CW1, ERLQ016CW1, ERSQ011AV1, ERSQ014AV1, ERSQ016AV1, RSQ011AY1, ERSQ014AY1, ERSQ016AY1
| Error Code | Description |
|---|---|
| A1 | Indoor unit HT & LT: Printed circuit board defect |
| A5 | Indoor unit LT: Liquid sensor error |
| A6 | Indoor unit HT: Water pump error |
| A9 | Indoor unit HT: Expansion valve drive error R410A circuit |
| AA | Indoor unit LT: Thermal protector in back up heater open |
| AC | Indoor unit LT: Thermal protector in cylinder open, cylinder over heat |
| AJ | Indoor unit HT: Capacity plug missing |
| C0 | Indoor unit LT: Water pump stopped but flow switch still made |
| C1 | Indoor Unit HT: Failure of transmission between the indoor printed circuit board and control board |
| C4 | Indoor unit HT & LT: Malfunction of liquid thermistor (R410A) |
| C5 | Cylinder HT: Malfunction of tank thermistor |
| C9 | Indoor unit HT: Return water temperature thermistor fault |
| CA | Indoor unit HT: Leaving water temperature thermistor error |
| CJ | Indoor unit HT: Malfunction of thermostat sensor in the remote controller |
| E1 | Outdoor unit HT & LT: Printed circuit board defect |
| E1-3 | Indoor unit HT: Pcb defect |
| E3-1 | Outdoor unit HT & LT: High Pressure |
| E3-12 | Indoor unit HT (R134A): High pressure |
| E4 | Outdoor unit HT & LT: Low Pressure (R410A) |
| E4-6 | Indoor unit HT: Low pressure (R134A) |
| E5 | Outdoor unit HT & LT: Compressor lock or service valves shut (R410A) |
| E5-6 | Indoor unit HT: Compressor lock (R134A) |
| E6 | Outdoor unit LT: Compressor malfunction, over current, failed to start |
| E7 | Outdoor unit HT & LT: Fan motor malfunction or locked |
| E8 | Outdoor unit LT: Compressor malfunction, over current, failed to start |
| E9 | Outdoor unit HT & LT: Expansion valve drive error (R410A) |
| E9-17 | Indoor unit HT: Expansion valve drive error K2E (R134A) |
| EA | Outdoor unit LT: 4 way valve failed to change over or indoor liquid line thermistor fault |
| EC | Cylinder LT: Domestic hot water cylinder thermistor fault |
| F3 | Outdoor unit HT & LT: Abnormal discharge pipe temperature or faulty thermistor (R410A) |
| F3-19 | Indoor unit HT: Abnormal discharge pipe temperature (R134A) |
| F6 | Outdoor unit LT: Condensing temperature too high or faulty thermistor (R410A) |
| H0 | Outdoor unit LT: Current sensor faulty, compressor disconnected or faulty outdoor printed circuit board (R410A) |
| H3 | Outdoor unit LT: High pressure switch activation, possible faulty HP switch or faulty printed circuit board (R410A) |
| H6 | Outdoor unit LT: Compressor start up failure (R410A) |
| H8 | Outdoor unit LT: Current transformer failure, outdoor printed circuit board fault (R410A) |
| H9 | Outdoor unit HT & LT: Malfunction of outside air thermistor R1T (R410A) |
| HC | Cylinder LT: Domestic hot water cylinder thermistor fault |
| J1 | Outdoor unit LT: Pressure sensor malfunction, pressure transducer (R410A) |
| J3 | Outdoor unit HT & LT: Malfunction of the discharge pipe thermistor (R410A) |
| J3-46 | Indoor unit HT: Malfunction of the discharge pipe thermistor R6T (R134A) |
| J5 | Outdoor unit HT & LT: Suction pipe thermistor error R3T R5T (R410A) |
| J5 | Indoor unit HT: Suction pipe thermister error R7T (R134A) |
| J6 | Outdoor unit HT & LT: Malfunction of thermistor for outdoor heat exchanger (R410A) |
| J7 | Outdoor unit HT & LT: Malfunction of liquid pipe thermistor on outdoor coil (R410A) |
| J8 | Outdoor unit LT: Malfunction of liquid pipe thermistor on outdoor coil (R410A) |
| J9 | Outdoor Unit HT: Malfunction of thermistor for subcooling heat exchanger gas pipe R4T (R410A) |
| JA | Outdoor unit HT: Malfunction of high pressure sensor X17A (transducer) (R410A) |
| JA-16 | Indoor unit HT: Malfunction of high pressure sensor X17A (transducer) (R134A) |
| JC | Outdoor unit HT: Malfunction of low pressure sensor X18A (transducer) (R410A) |
| JC-16 | Indoor unit HT: Malfunction of low pressure sensor X18A (transducer) (R134A) |
| L1 | Outdoor unit HT & LT: Malfunction of printed circuit board A1P (R410A) |
| L1-30 | Indoor unit HT: Malfunction of printed circuit board A4P (R134A) |
| L3 | Outdoor unit LT: Electrical switch box temperature rise >85oC (R410A) |
| L4 | Outdoor Unit HT & LT: Malfunction of inverter radiating fin temperature rise >83oC (R410A) |
| L4-8 | Indoor Unit HT: Malfunction of inverter radiating fin temperature rise >83oC R8T (R134A) |
| L5 | Outdoor Unit HT & LT: Malfunction of inverter compressor lock, over current (R410A) |
| L5-13 | Indoor Unit HT: Malfunction of inverter compressor lock, over current (R134A) |
| L8 | Outdoor Unit HT & LT: Malfunction of inverter compressor overload, current abnormal (R410A) |
| L8-10 | Indoor Unit HT: Malfunction of inverter compressor overload, current abnormal (R134A) |
| L9 | Outdoor Unit HT & LT: Malfunction of inverter start up, defect compressor or differential, stall prevention (R410A) |
| L8-9 | Indoor Unit HT: Malfunction of inverter start up, defect compressor or differential, stall prevention (R134A) |
| LC | Outdoor Unit HT & LT: Malfunction of transmission between inverter and control board A1P or A2P (R410A) |
| LC-29 | Indoor Unit HT: Malfunction of transmission between inverter and control board A4P or A5P (R134A) |
| LH-2 | Indoor Unit HT: Malfunction of inverter pcb (R134A) |
| P1 | Outdoor unit HT & LT: High Voltage of capacitor in main inverter circuit (R410A) |
| P1-6 | Indoor unit HT: High Voltage of capacitor in main inverter circuit (R134A) |
| P4 | Outdoor unit LT: Electrical switch box fin thermistor fault (R410A) |
| PJ | Indoor unit LT: Capacity adapter not installed (R410A) |
| PJ-11 | Indoor unit HT: Incorrect combination of indoor printed circuit board or capacity adapter not installed (R134A) |
| U0 | Outdoor unit HT & LT: Low pressure drop due to refrigerant shortage or electronic expansion valve failure (R410A) |
| U2 | Outdoor unit HT & LT: Power supply insufficient or Instantaneous failure, low or high voltage detected (R410A) |
| U2-20 | Indoor unit HT: Power supply insufficient or Instantaneous failure, low or high voltage detected |
| U2-20 | Indoor unit HT: High low voltage problem |
| U2-21 | Indoor unit HT Converter problem (R134A) |
| U4 | Outdoor Unit HT & LT: Malfunction of transmission between indoor and outdoor unit (R410A) |
| U4-4 | Indoor Unit HT: Malfunction of transmission between the indoor and outdoor unit |
| U4-4 | Indoor Unit HT: DIII Communication error (R134A) |
| U5 | Indoor Unit HT & LT: Malfunction of transmission between the remote control and indoor unit |
| U5-0 | Indoor Unit HT: Malfunction of transmission between the remote controllers main and sub controller (R134A) |
| U7 | Outdoor Unit LT: Signal transmission failure on outdoor printed circuit board faulty (R410A) |
| U8 | Indoor Unit HT: Malfunction of transmission between the main and sub controller (R134A) |
| UA | Indoor Unit HT: Excessive number of indoor units or mis matched board replaced and capacity not set (R134A) |
| UA-13 | Outdoor Unit HT: Excessive number of indoor units or mis matched board replaced and capacity not set (R410A) |
| UA | Indoor & Outdoor Unit LT: Interconnecting wiring crossed (R410A) |
| UF | Indoor Unit HT: Unit has not been initialised up to 10 minutes |
| UF-6 | Indoor Unit HT: QA wiring problem |
| UF-10 | Indoor Unit HT: Transmission problem with outdoor unit (R134A) (R410A) |
| UF | Outdoor Unit LT: Transmission problem between indoor & outdoor unit or gas shortage (R410A) |
| UH-0 | Indoor Unit HT: Defect of transmission wiring,indoor printed circuit board failure or outdoor printed circuit board failure (R134A) (R410A) |
| 7H | Indoor unit LT: Flow switch activated, water flow rate too low or blocked inlet strainer |
| 80 | Indoor unit LT: Inlet water temperature thermistor error |
| 81 | Indoor unit LT: Outlet water temperature thermistor error |
| 89 | Indoor unit LT: Outlet water temperature thermistor error, freeze up or water temperature too low |
| 8H | Indoor unit LT: Outlet water temperature too high, back up heater welded shut or thermistor out of calibration |