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ErrBase

Daikin Minisplit Error Codes

All Daikin minisplit error codes with step-by-step troubleshooting, multimeter specs, and OEM part numbers.

27 error codes

CodeMeaning
A3A3 fires when condensate water overflows the primary drain path and reaches the secondary backup pan inside the indoor unit. A float switch in that pan rises with the water level and kills the compressor. Daikin builds this redundancy in specifically to prevent water damage if the primary drain ever gets blocked.
moderatebeginner
BLUE-LIGHTThe blue LED on newer Daikin models (like the Emura and FTXM series) indicates Wi-Fi connectivity status or Econo mode activation. When it blinks, the onboard Wi-Fi module is either searching for your network or waiting to pair with the Daikin Online Controller app. It's not an error, just a status light.
lowbeginner
E0E0 means one of the system's safety devices tripped to prevent serious hardware damage. It's Daikin's catch-all code for when a safety switch or sensor activated but a more specific code isn't available. The outdoor unit basically said it's done before something expensive blew.
highintermediate
E11E11 means the inverter board detected a mismatch between two compressors in a tandem outdoor unit. One's either not starting, drawing wildly different current, or the communication between the two driver circuits broke down. This code doesn't exist on single-compressor systems.
criticaladvanced
E3E3 indicates the refrigerant system high-side pressure has exceeded the safe operating limit. The high pressure switch on the outdoor unit has tripped, shutting down the compressor to prevent system damage or safety hazard.
highintermediate
E4E4 fires when the suction-side pressure sensor reads below safe minimum, usually around 15-20 PSI on R-410A systems. The control board cuts the compressor to prevent it from running dry. Think of it like an oil pressure warning in your car, but for refrigerant.
highadvanced
E5E5 indicates the compressor overload relay has tripped, meaning the compressor is drawing more current than its rated capacity for an extended period. This is distinct from L5 (instantaneous trip) - E5 is a sustained overload condition.
highintermediate
E6The inverter board pulsed power to the compressor motor, but the rotor didn't turn. Either something's physically stopping it, like liquid slugging or seized bearings, or the winding resistance is off and the board shut down to protect itself from an overcurrent condition it couldn't handle.
criticaladvanced
E7The outdoor unit's DC fan motor either failed to start, stalled during operation, or is pulling more current than the inverter board expects. Daikin monitors fan speed via a feedback signal, so if the blade's cracked and wobbling, or the bearings are worn down, the board sees an out-of-spec signal and shuts everything down before something worse breaks.
highintermediate
F3F3 means the discharge pipe thermistor has detected temps above roughly 120C (248F) at the compressor output. When the system's starving for refrigerant, the gas leaving the compressor is superheated way beyond normal. The thermistor mounted right on that pipe catches it and kills the unit before it does real damage.
highadvanced
GREEN-LIGHTThe green LED on a Daikin indoor unit indicates operational status. Different blink patterns have different meanings: steady on or fast blink (2Hz) means the unit is running normally, slow blink (0.5Hz) means standby, and specific blink counts between pauses indicate error codes on models without numeric displays.
lowbeginner
HUBWhen one of these codes fires, the control board detected something outside its normal operating window and shut the system down to protect itself. Each letter prefix maps to a specific system: U is the communication bus between units, E is compressor protection, F is temperature sensing, L is the inverter drive, and A covers drain and airflow issues.
moderatebeginner
L1L1 means the outdoor unit's inverter board caught a failure inside its own circuitry. The inverter converts incoming AC to variable-frequency DC to spin the compressor at different speeds. When it detects an internal fault, whether it's a blown IGBT, a failed gate driver, or a cracked solder joint, it throws L1 and shuts the whole thing down.
criticaladvanced
L5L5 indicates an instantaneous overcurrent trip on the compressor circuit. Unlike U0 which builds over time, L5 is a sudden spike that triggers immediate shutdown. This often indicates a phase-to-phase short in the compressor windings or a failed inverter power transistor on the outdoor board.
criticaladvanced
NOT-COOLINGWhen your Daikin runs but can't cool, the inverter-driven compressor is either getting starved of airflow, losing capacity from a low refrigerant charge, or it's shutting itself down on a protection fault. The system modulates compressor speed based on load, so when something's off, it'll often keep running but just never hit your setpoint.
moderatebeginner
NOT-HEATINGIn heat pump mode, your Daikin's outdoor unit acts like a refrigerator running in reverse, pulling heat energy from cold outside air and pumping it indoors. When that stops working, it's usually because the outdoor coil iced over and blocked airflow, the refrigerant charge dropped too low to move meaningful heat, or the system's running below its rated outdoor temperature range.
moderatebeginner
NOT-WORKINGThe Daikin outdoor unit acts as the main power hub. It takes 240V from your breaker, converts it internally, and sends both power and communication signals to the indoor head through a 3-wire cable. When the outdoor board dies or a fuse blows, the indoor unit loses everything simultaneously and goes completely dark.
highintermediate
ORANGE-LIGHTThe orange LED on a Daikin indoor unit serves dual purpose: it indicates timer mode when steady or slow-blinking, and error codes when blinking in counted patterns. A continuously blinking orange light typically means a fault condition.
moderatebeginner
RED-LIGHTA red LED on a Daikin indoor unit means the system caught something wrong and locked itself out to prevent damage. It's the most serious indicator on the unit. The blink count before each pause is your actual diagnostic code, so counting those flashes is the first thing you do.
highintermediate
RESETWhen this triggers, the mini-split's control board hit a fault condition, lost communication between the indoor and outdoor units, or got into a frozen state where it won't respond to commands. Cutting power forces the microprocessor to restart from scratch and re-establish the communication link between the two units.
lowbeginner
TROUBLESHOOTSystematic troubleshooting guide for Daikin mini-split systems covering the most common issues: not cooling, not heating, error codes, unusual noises, ice buildup, and communication faults between indoor and outdoor units.
moderatebeginner
U0U0 on a Daikin mini-split signals that the compressor is drawing excessive current, which typically indicates low refrigerant charge or a mechanical compressor fault. Daikin inverter compressors modulate speed continuously, and U0 triggers when current draw exceeds the safe threshold at any operating speed.
highadvanced
U2U2 indicates a general power supply voltage fault affecting the entire system. While U9 is specific to the outdoor unit, U2 can trigger from voltage issues at either the indoor or outdoor unit power feed.
moderateintermediate
U3U3 means one of the outdoor unit's thermistors is reading out of range, either open circuit (OL on your meter) or shorted to nearly zero ohms. Daikin monitors ambient air temp, coil temp, and discharge pipe temp simultaneously. Any one of those going bad triggers this code and shuts the compressor down.
moderateintermediate
U4U4 fires when the indoor unit stops receiving data packets from the outdoor unit over Daikin's 2-wire serial bus (S1 and S2 terminals). The system's basically saying it's been trying to call and nobody's picking up. It can't run the compressor or reversing valve without that communication link, so the whole thing locks out.
highintermediate
U9U9 fires when the outdoor unit's inverter board detects incoming voltage dropping below roughly 187V on a 208-230V system. That monitoring circuit watches incoming voltage constantly, and when it dips too low, it cuts power to protect the compressor and inverter components from damage that would otherwise be permanent.
moderateintermediate
WONT-TURN-ONA Daikin mini-split that won't turn on has zero response to the remote and no display on the indoor unit. It's basically a power delivery failure, not a refrigerant or mechanical fault. The indoor head depends entirely on the outdoor unit to pass power through, so when the outdoor side loses power, everything goes dark at once.
highbeginner