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Daikin Air Conditioner L4 Error Code

Inverter heat sink overheating. What it means, which models show it, and how to clear it, easiest fix first.

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L4
Moderate DIY

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.

Compatible models

Daikin doesn't publish a model list for this code; it appears on Daikin air conditioners with a digital display. Check your owner's manual.

Also shown as

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.

Difficulty

Start with the safe checks below; a worn part may need replacing.

Safety first: unplug the air conditioner (or switch off its breaker) before touching filters, hoses or panels. If you smell burning or gas, or see water near the outlet, stop and call a professional.

How to fix Daikin L4

  1. 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.

  2. 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 linked to L4

These are the parts most often behind this code. Tap one to see what it does and the signs it is failing.

Order parts by your full model number so they fit.

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.

Which Daikin models show the L4 code?

Daikin doesn't publish a model list for this code; it appears on Daikin air conditioners with a digital display. Check your owner's manual.

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.

Other Daikin air conditioner codes

Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.

Sources we checked