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Daikin Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
- 7H-01 The 7H-01 code appears on Daikin Altherma heat pump controllers when the system's flow sensor detects insufficient… Read more →
- 7H-04 The 7H-04 code indicates that the Daikin Altherma heat pump has detected an abnormal or insufficient water flow… Read more →
- 7H-05 The 7H-05 fault code on Daikin Altherma heat pumps indicates that the system has detected insufficient water flow… Read more →
- 7H-06 The 7H-06 code on Daikin Altherma heat pumps signals that the system has detected insufficient water flow through the… Read more →
- 80-00 The 80-00 code indicates that the Daikin Altherma heat pump has detected a problem with the R4T thermistor — the sensor… Read more →
- 81-00 The 81-00 code indicates that the heat pump's indoor hydronic unit has detected an abnormal reading from the leaving… Read more →
- 89-01 The 89-01 code indicates that your Daikin heat pump has detected a freeze-up condition at the brazed plate heat… Read more →
- 89-02 Fault code 89-02 appears on Daikin Altherma heat pumps when the refrigerant-side temperature of the brazed-plate heat… Read more →
- 89-03 The 89-03 code appears on Daikin Altherma heat pumps when the evaporator temperature (Te) drops too low during a… Read more →
- 8F-00 The 8F-00 code tells you that the heat pump's control system has lost confidence in the reading from the second suction… Read more →
- 8H-00 The 8H-00 code (also displayed as H8 or H8-00 on Daikin controllers) indicates that the outdoor unit's current… Read more →
- 8H-01 The 8H-01 code appears on Daikin Altherma 3 H HT F heat pumps and indicates that the system has detected dangerously… Read more →
- 8H-02 The 8H-02 code means the safety thermostat within the mixed water circuit has physically tripped because the water… Read more →
- 8H-03 The 8H-03 fault code indicates that the heat pump's internal safety thermostat has detected dangerously high water… Read more →
- A1-00 The A1-00 code (also logged simply as A1) indicates that the indoor unit's main control board — sometimes called the… Read more →
- A1-01 The A1-01 fault code on a Daikin heat pump points to a failure of the indoor unit's main control board (PCB).… Read more →
- A5-00 The A5-00 fault code indicates that the indoor heat exchanger has exceeded its safe operating limits — either… Read more →
- AA-00 The AA-00 fault code on a Daikin Altherma heat pump indicates that the back-up heater's thermal protector (Q1L) has… Read more →
- AA-01 The AA-01 code appears on Daikin Altherma heat pumps and can carry one of several related meanings depending on the… Read more →
- AA-02 The AA-02 code on a Daikin Altherma heat pump indicates that the backup (booster) heater has exceeded its safe… Read more →
- AC-00 The AC-00 (or simply '00') code on Daikin heat pumps has two distinct meanings depending on how and when it appears. If… Read more →
- AH-00 The AH-00 code indicates that the heat pump's automatic tank disinfection cycle did not complete successfully. Daikin… Read more →
- AJ-03 The AJ-03 warning appears on Daikin Altherma heat pumps when the domestic hot water (DHW) cylinder has taken longer… Read more →
- C0-00 The C0-00 fault code appears on Daikin Altherma air-source heat pumps when the flow sensor detects water movement… Read more →
- C0-01 The C0-01 code appears on Daikin Altherma heat pumps when the water flow sensor continues to detect movement in the… Read more →
- C0-02 The C0-02 fault code appears on Daikin Altherma heat pumps when the system's flow sensor or flow switch reports a… Read more →
- C4-00 The C4-00 fault code indicates that the indoor heat exchanger thermistor — the sensor responsible for monitoring the… Read more →
- C5-00 The C5-00 fault code indicates that the indoor unit's refrigerant pipe thermistor — the temperature sensor that… Read more →
- CJ-02 The CJ-02 fault code on Daikin heat pump systems points to an abnormality with the room temperature thermistor built… Read more →
- E1-00 The E1-00 code on a Daikin heat pump signals a fault with the outdoor unit's printed circuit board (PCB) — the control… Read more →
- E2-00 The E2-00 code means the Daikin Altherma outdoor unit's main PCB has detected an unwanted electrical current flowing to… Read more →
- E3-00 The E3-00 code indicates that the high-pressure switch (HPS) on your primary outdoor unit has triggered a protective… Read more →
- E3-24 The E3 fault code on Daikin heat pumps signals that the high-pressure switch (HPS) on the refrigerant circuit has… Read more →
- E4-00 The E4-00 fault code indicates that the low-pressure switch (LPS) on your Daikin heat pump's outdoor unit has activated… Read more →
- E5-00 The E5-00 fault code on a Daikin heat pump indicates that the system's overload protector (OL) has triggered a… Read more →
- E6-00 The E6-00 code on a Daikin heat pump signals that the outdoor unit has detected a compressor lock or start-up failure.… Read more →
- E7-00 The E7-00 fault code indicates that the outdoor unit's fan motor system has detected a problem and stopped working… Read more →
- E8-00 The E8-00 fault code means the outdoor unit's inverter has detected an abnormally high current draw from the compressor… Read more →
- E9-00 The E9-00 code signals that the heat pump's outdoor unit has detected a fault with the Electronic Expansion Valve (EEV)… Read more →
- EA-00 The EA-00 code appears on Daikin heat pumps when the outdoor unit detects a problem with the four-way valve — the… Read more →
- EC-00 The EC-00 fault code indicates that the domestic hot water (DHW) tank thermistor has detected a water temperature… Read more →
- F6-00 The F6-00 fault code signals that your Daikin heat pump's outdoor unit has detected abnormally high refrigerant… Read more →
- H0-00 The H0-00 code indicates that the heat pump's outdoor unit has detected an abnormal reading from the voltage or current… Read more →
- H1-00 The H1-00 code on Daikin Altherma heat pumps indicates a problem with the optional indoor ambient temperature sensor… Read more →
- H3-00 The H3-00 fault on a Daikin heat pump indicates that the high pressure switch (HPS) has detected an open circuit… Read more →
- H6-00 The H6-00 fault code indicates that the outdoor unit's inverter drive has lost rotor-position feedback from the… Read more →
- H8-00 The H8-00 fault code indicates that the outdoor unit has detected an abnormality in the compressor input current… Read more →
- H9-00 The H9-00 fault code points to a problem with the outdoor air temperature sensor — known internally as the R1T… Read more →
- HC-00 The HC-00 fault code on a Daikin heat pump (typically a Daikin Altherma series) signals that the system has detected a… Read more →
- HJ-08 The HJ-08 code appears on Daikin boilers when the heating system's water pressure has climbed above the safe operating… Read more →
- HJ-09 The HJ-09 code appears on Daikin Altherma heat pumps when the water pressure in the heating circuit drops below the… Read more →
- HJ-10 The HJ-10 code appears on certain Daikin Altherma heat pump and Altherma H Hybrid systems. It sits within the HJ… Read more →
- J3-00 The J3-00 fault code indicates that the outdoor unit's discharge pipe thermistor has reported a reading that is outside… Read more →
- J5-00 The J5-00 fault code points to a problem with the suction pipe thermistor on the outdoor unit. This sensor monitors the… Read more →
- J6-00 The J6-00 code signals that your Daikin heat pump has detected an abnormality in the outdoor unit's heat exchanger… Read more →
- J7-00 The J7-00 fault code indicates that the outdoor unit has detected an abnormal reading from the intermediate heat… Read more →
- J8-00 The J8-00 fault code points to a problem with the liquid pipe thermistor located on the outdoor unit. This sensor… Read more →
- JA-00 The JA-00 code indicates that the high pressure sensor (also called the high pressure transducer) on the master outdoor… Read more →
- L1-00 The L1-00 code indicates that the heat pump's outdoor unit has detected a fault within its inverter printed circuit… Read more →
- L3-00 The L3-00 fault code signals that the outdoor unit's electrical compartment has reached a dangerously high temperature… Read more →
- L4-00 The L4-00 fault indicates that the inverter radiation fin (heatsink) inside the outdoor unit has reached an abnormally… Read more →
- L5-00 The L5-00 code is triggered when the outdoor unit's inverter board detects an instantaneous current spike on its output… Read more →
- L8-00 The L8-00 fault code appears on Daikin heat pumps when the inverter detects that the compressor is drawing an… Read more →
- LC-00 The LC-00 fault code indicates that the outdoor unit's main control PCB has lost reliable communication with the… Read more →
- PJ-00 The PJ-00 fault code flags a configuration or hardware problem with the outdoor unit's main PCB. Specifically, it… Read more →
- U0 The U0 fault code indicates that your Daikin system has detected symptoms consistent with a refrigerant shortage.… Read more →
- U2-00 The U2-00 fault code on Daikin Altherma heat pumps indicates that the unit has detected an abnormal condition in its… Read more →
- U3-00 The U3-00 code appears on Daikin heat pump systems when the unit has entered normal operation without the mandatory… Read more →
- U4-00 The U4-00 fault code signals that the indoor unit and outdoor unit have lost the ability to communicate with one… Read more →
- U5-00 The U5-00 fault code indicates that the remote controller has lost its communication link with the indoor unit's… Read more →
- U7-00 The U7-00 code indicates that the main control PCB and the inverter PCB inside the outdoor unit have lost the ability… Read more →
- UA-00 The UA-00 code on Daikin heat pump systems indicates a system combination or configuration problem — typically that the… Read more →
- UF-00 The UF-00 code indicates that the Daikin system has not been correctly set up or commissioned. Specifically, the heat… Read more →