Daikin Error Code E3: High Pressure Switch Tripped (Meaning, Causes, Fixes)
What the code means
Daikin's SkyAir inverter service manual SiUS25-501 titles E3 "Outdoor Unit: Actuation of High Pressure Switch." The outdoor board watches the contact of the high pressure protection switch (HPS), and the error is set when that contact opens enough times for the current operating mode. Before it gets that far, the unit tries to protect itself: it slows the inverter compressor when the high-pressure sensor reads high, goes into high-pressure standby, and only trips the switch and shows E3 when pressure keeps climbing (in cooling, Daikin says three high-pressure standbys within 30 minutes lead straight to E3). Daikin's Simple Self-Diagnosis code list uses the same meaning, "Actuation of high pressure switch (HPS)," across its split, SkyAir and VRV equipment. E3 isn't in the error table for Daikin's Entra wall-mount mini splits, which use A5 for high pressure control, so check your model's manual if you see E3 on a wall-mount unit.
Likely causes
- A dirty or blocked outdoor heat exchanger (coil), so the unit can't get rid of heat in cooling. This is the first cause in Daikin's self-diagnosis list.
- An outdoor fan that isn't running or is running poorly, also listed in Daikin's E3 troubleshooting notes.
- Too much refrigerant in the system, which Daikin names for E3 both in troubleshooting and as an installation mistake.
- Gas-side or liquid-side shutoff valves left closed at the outdoor unit after installation, Daikin's other E3 installation cause.
- Clogged refrigerant piping, or a defective connector contact at the high pressure switch.
- A defective high pressure switch, a faulty high pressure sensor, or a defective outdoor unit PC board (A2P on SkyAir units).
- An instantaneous power failure, which Daikin lists as a possible cause when the unit runs normally after a restart.
Safe DIY checks
Turn off the power at the outdoor disconnect before cleaning the coil or touching any connector; the outdoor inverter board can hold a dangerous charge after power is removed. Refrigerant recovery and recharging must be done by a certified technician (in the US, EPA Section 608 certification is required). Don't keep resetting a unit that trips on high pressure.
- Turn the system off and look at the outdoor unit. Clear leaves, grass clippings, snow, covers or anything stacked against it, and keep at least a couple of feet open around the coil.
- If the outdoor coil is visibly dirty, switch off the outdoor disconnect and gently clean it with a no-rinse coil cleaner or a garden hose at low pressure, spraying from the inside out if you can reach it. Don't bend the fins.
- Restore power and restart. Daikin's flowchart treats a unit that runs normally after a restart as a past power blip or a one-time safety trip, but says the refrigerant system should still be rechecked.
- Watch the outdoor fan after a restart. If the compressor starts but the fan doesn't spin, turn the unit off and call for service.
- If E3 shows up right after a new installation, call the installer: closed shutoff valves or an overcharge are installation fixes Daikin calls out by name.
- If E3 comes back after cleaning and a reset, stop running the system and call a licensed HVAC technician.
🛠 When to call a pro
- Following Daikin's SiUS25-501 flowchart with power off: confirming the HPS connectors are plugged into the outdoor inverter PC board (A2P) and reconnecting if not.
- Checking whether contact S1PH (the high pressure switch) is open. If it is, the switch actually tripped, so checking the outdoor coil, outdoor fan, refrigerant charge and high pressure sensor.
- If the switch is closed and the unit runs normally after a restart, treating it as an instantaneous power failure or past safety trip and rechecking the refrigerant system; if it still fails, replacing the outdoor unit PC board.
- Verifying both shutoff valves are fully open, and recalculating the correct refrigerant charge for the piping length, recovering and recharging to the proper amount if the system is overcharged.
- Checking for clogged refrigerant piping and a defective high pressure switch, per Daikin's self-diagnosis code list.
Parts that commonly fix it
Always match the part number to your exact model.
Coil cleaner
For a dirty outdoor coil, the first E3 cause in Daikin's list; use a no-rinse or foaming cleaner made for AC coils.
Search eBay →Outdoor fan motor
Only if the outdoor fan isn't running or runs too slowly; match it to your exact Daikin outdoor unit model.
Search eBay →Outdoor control board
Daikin's last step when the high pressure switch is closed and E3 keeps returning; order by your outdoor unit model number.
Search eBay →Sources
- Daikin SkyAir Inverter service manual SiUS25-501, 4.14 "E3" Outdoor Unit: Actuation of High Pressure Switch (p. 110), high pressure protection control, and installation nonconformity table, Daikin Comfort
- Daikin Industries, Simple Self-Diagnosis by Malfunction Code (E3 actuation of high pressure switch: dirty outdoor heat exchanger, defective HPS, clogged refrigerant piping, defective connector contact)
- Daikin Entra wall mount service manual FTK(X)B/RK(X)B AXVJU, 3.3 inverter error code table (no E3; A5 antifreeze protection or high pressure control), Daikin Comfort
Last reviewed 2026-10-24. Always confirm against the manual for your exact model number.