Mini-split & heat pump error codes and fixes, in plain English
Look up your brand’s fault code, understand what each symptom means, and learn exactly what’s safe to fix yourself — and when to call a licensed pro.
Find your mini-split’s error code
Pick your brand for a quick-lookup table of codes, meanings, and safe first steps.
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Error codes by brand
Look up any brand fault code and what to do about it.
Explore →Mini-split troubleshooting
Not cooling, leaking, freezing up, won’t turn on — fixes by symptom.
Explore →Operation & efficiency
How heat pumps work and how to run them efficiently.
Coming soonMaintenance
Filters, coils, drain lines — keep it running and warranty-safe.
Coming soonBuying & cost
Costs, sizing, brands, and incentives before you buy.
Coming soonWhat are mini-split error codes?
Mini-split and heat pump error codes are short letter-and-number messages
(like E6, P4, or U4) that the system
shows on the indoor unit’s display or by blinking its LED lights when it
detects a fault. The code points to the affected area — communication,
sensors, the drain, refrigerant, or the compressor — so you can tell at a
glance whether it’s a simple homeowner fix (a dirty filter, a clogged drain,
a tripped breaker) or a job for a licensed technician. The meaning of each
code varies by brand and model, so always start by identifying your brand,
then confirm the exact code against your unit’s manual. Refrigerant and
high-voltage work requires EPA-608 certification and should never be a DIY task.