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Lennox Mini-Split Error Codes: What Each Code Means

by Dua Jones May 13, 2026

Lennox mini-splits display fault codes on the indoor unit's LED display or via the iComfort connected thermostat system for WiFi-enabled installations. Lennox's ductless error code system uses alphanumeric designations consistent with the broader Lennox HVAC platform. This guide covers the most common Lennox mini-split error codes and recommended first responses.

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Common Lennox Mini-Split Error Codes

Error Code	Meaning	DIY Fix?	First Step
E1 / 204	High pressure protection	Partially	Clear outdoor unit airflow; reset at breaker
E2 / 201	Low pressure / refrigerant issue	No	Call Lennox dealer — refrigerant leak check
E4 / 229	Compressor overload / overheating	Partially	Clear outdoor unit; reset; call tech if recurring
E6 / 232	Communication error (indoor to outdoor)	Partially	Reset at breaker; check signal wire connections
F1 / 111	Indoor intake temperature sensor fault	No	Reset; call tech if recurring — thermistor
F2 / 112	Indoor coil temperature sensor fault	No	Call technician — thermistor replacement
P1 / 411	Freeze protection — indoor coil too cold	Yes	Clean filter; let coil thaw 2–3 hrs; restart
P4 / 551	Drain fault / condensate blockage	Yes	Clear the condensate drain line

iComfort Connected System Diagnostics

Lennox mini-splits connected to the iComfort smart control platform display error codes directly within the iComfort app or thermostat interface with plain-language descriptions. This makes diagnosis more accessible than counting LED blinks or decoding two-digit codes. If you have an iComfort-connected installation, check the app first — it will display the active fault description and may provide a recommended action before you need to reference a service manual.

Frequently Asked Questions

My Lennox shows a three-digit code (e.g., 204) — what does that mean?

Lennox ductless systems may display three-digit diagnostic codes when connected to compatible control interfaces. These codes are Lennox-proprietary and documented in the specific model's service manual. Code 204 typically corresponds to high pressure protection (equivalent to E1). Always reference your exact model's documentation for definitive code interpretation.

Who can service a Lennox mini-split?

Lennox ductless systems should be serviced by a Lennox Factory Authorised Dealer. Using non-Lennox dealers may affect warranty coverage. Contact Lennox customer service or use their dealer locator to find certified service in your area.