Daikin Earlier Daikin Altherma fault codes
The R410A Altherma LT split (ERLQ outdoor unit with an EHVH/EHVX or EHBH hydrobox) and its predecessors. The 2018 installer guide already prints the two-part code; older displays and Daikin UK’s owner leaflet use the bare two characters. Same fault families as the newer units.
Codes on the Earlier Daikin Altherma follow the same Daikin scheme as the rest of the range. Where a code behaves differently on this generation, the code page says so.
Daikin fault codes
Every published Daikin code. Open a code to see which models and years it applies to.
- Bill has jumpedThe most important heat pump fault has no code. If your electricity cost has stepped up with no change in habits, the backup heater is probably doing the work.Get it checked
- Ice on the outdoor unitNormal in cold damp weather, and the unit clears it itself. Daikin specifically forbid helping — no hot water, no de-icer, no scraping.Get it checked
- 7HA water flow problem. The sub-code matters more than the code: 7H-01 clears itself, 7H-04 to 7H-06 need a manual reset, 7H-08 is the pump, and 7H-07 is the unit freeing a stuck pump.Get it checked
- Water at the tap is too coldDaikin give two causes and a remedy that costs money. Before using it, check what your schedule is actually asking the cylinder to do.Get it checked
- U0Shortage of refrigerant in the Altherma outdoor unit. Daikin’s own checklist ends with a leak test, the circuit is sealed, and on an R32 unit this is F-Gas certified work by law.Get it checked
- U4Indoor/outdoor unit communication problem. Daikin’s checks start with the power supply and the wiring between the two boards, and the published reset is a power reset at the outdoor unit.Get it checked
- AHThe tank disinfection cycle did not complete: the setpoint was not reached within six hours or not held long enough. The unit keeps running, and Daikin’s first cause is hot water drawn mid-cycle.Get it checked
- E3The outdoor unit’s high pressure switch has opened. Daikin list a closed stop valve, a faulty sensor or switch, overcharge, moisture, a blockage and the fan, and require a manual reset.Get it checked
- A5High pressure peak cut in heating, freeze protection in cooling. On an Altherma, Daikin’s first four checks are all water-side: pressure, flow, stop valves and air. Not the indoor filter of an air conditioner.Get it checked
- H4Malfunction of the low pressure switch, a protection device on the refrigerant side of the outdoor unit. Daikin publish the name and nothing an owner can act on; it is certified work.Get it checked
- C0Flow sensor malfunction: the sensor sees water moving 45 seconds after Daikin’s pump has stopped. Low pressure, air and an external pump running are on the list before the sensor itself.Get it checked
- 89Heat exchanger frozen. 89-02 and 89-03 are warnings that reset themselves; three of them within half an hour of each other lock the unit out with 89-01, which needs an engineer.Get it checked
- E7The outdoor unit fan did not start within thirty seconds of being told to. Daikin’s checks are the fan motor and the main PCB; what you can check is whether anything is stopping the blades.Get it checked