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Daikin Air Conditioner L4 Error Code
Inverter heat sink overheating. Here is what it means and how to clear it, easiest fix first.
The cooling fins on the outdoor inverter board got too hot. Restricted airflow around the outdoor unit, very high outdoor temperatures, an outdoor fan problem or a faulty fin sensor can cause it.
P4 means the fin temperature sensor itself has failed, rather than the fins being hot. Daikin uses this code across its residential split, SkyAir and VRV ranges, but the exact meaning and causes can vary by series, model year and region, so confirm it in your unit's manual. How to read it: most Daikin ductless wall units only blink the operation lamp. On remotes such as the ARC433 series, press and hold the timer Cancel button for roughly 5 seconds until 00 blinks on the screen, then press Cancel again one step at a time; when the indoor unit answers with a long continuous beep, the code showing is the stored fault. SkyAir and VRV wireless remotes use a different sequence with the Inspection/Test, up/down and MODE buttons, and wired wall controllers usually show the code on their screen.
How to fix Daikin L4
Clear around the outdoor unit
With the breaker off, remove leaves, grass clippings, snow or anything stored against the outdoor unit, and keep about 2 ft (60 cm) clear on all sides. Brush loose debris off the outside of the coil fins by hand or with a soft brush; do not use a pressure washer or bend the fins. Shade can help, but don't box the unit in.
Reset the power at the breaker
Switch the system off with the remote, then turn off its circuit breaker in your home's main panel. On a very hot day, leave it off for about 30 minutes so the electronics can cool, then switch the breaker back on and restart the unit.
When to call a technician
If L4 keeps appearing with clear airflow, an HVAC technician should check the outdoor fan and inverter board.
Parts that commonly cause L4
- outdoor fan motor
- inverter board
- radiation fin thermistor
Order parts by your exact model number so they fit.
Other Daikin air conditioner codes
- U4Indoor and outdoor units can't communicate
- U0Low refrigerant or restricted refrigerant flow
- U2Power supply voltage problem
- UAIndoor and outdoor units don't match
- A1Indoor unit control board fault
- A3Condensate water level too high
- A5Freeze-up or overheat protection
- A6Indoor fan motor fault
- C4Indoor coil temperature sensor fault
- C9Indoor room air temperature sensor fault
- E1Outdoor unit control board fault
- E5Compressor overload or lock-up protection
- E6Compressor won't start
- E7Outdoor fan motor fault
- E8Compressor current too high
- F3Compressor discharge temperature too high
- F6High pressure in cooling mode
- H6Compressor position sensing error
- L5Inverter output overcurrent
Frequently asked questions
What does L4 mean on a Daikin air conditioner?
The cooling fins on the outdoor inverter board got too hot. Restricted airflow around the outdoor unit, very high outdoor temperatures, an outdoor fan problem or a faulty fin sensor can cause it.
Can I fix Daikin L4 myself?
Often. The first steps above are safe checks a homeowner can do. If they don't clear L4, the cause is likely a worn part that needs replacing.
What if L4 keeps coming back?
A code that returns after a reset and the checks above usually means a part is wearing out. Note when L4 appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.
Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.