DIY HVAC Tools

Lennox mini split error codes

Lennox mini splits are built by Midea and use Midea's code sets. MPA, MPB and MLA single-zone units show classic two-character codes on the indoor unit (E1, P4); the MCB and MWCB series show four-character codes (EL 01, PC 04); and multi-zone outdoor units have their own display with a separate table.

Covers: MPA / MPB / MLA single-zone, MPA / MPB / MLA multi-zone, MCB / MWCB, MWMA / MWMB, MCFA / MCFB, MMDA / MMDB.

Type it exactly as the unit shows it. Not sure which brand? It is printed on the front of the indoor unit.

All Lennox codes

61 codes. Type to filter the list.

CodeMeaningTypeFix
E0MPA / MPB / MLA indoor unit display: Indoor unit EEPROM parameter error
multi-zone outdoor unit display: Outdoor unit EEPROM parameter error (outdoor display)
FaultDIY checks
E1Communication error between indoor and outdoor unitsFaultDIY checks
E2MPA / MPB / MLA indoor unit display: Zero-crossing signal detection error
multi-zone outdoor unit display: Communication error between the outdoor unit and the indoor units (outdoor display)
FaultDIY checks
E3MPA / MPB / MLA indoor unit display: Indoor fan speed out of control (indoor fan motor fault)
multi-zone outdoor unit display: Communication error between outdoor main board and IPM board (outdoor display)
FaultDIY checks
E4MPA / MPB / MLA indoor unit display: Indoor room temperature sensor (T1) open or short circuit
multi-zone outdoor unit display: Outdoor temperature sensor fault: coil (T3), ambient (T4), discharge (T5) or a zone coil outlet (T2B)
FaultDIY checks
E5MPA / MPB / MLA indoor unit display: Evaporator coil temperature sensor (T2) open or short circuit
multi-zone outdoor unit display: Over-voltage or under-voltage protection (outdoor display)
VariesDIY checks
ECRefrigerant leak detected (low refrigerant charge)FaultDIY checks
F0Overload current protection (compressor over-current)ProtectionDIY checks
EBCommunication error between indoor main board and display boardFaultDIY checks
EFIntelligent eye (occupancy sensor) module errorFaultDIY
F1MPA / MPB / MLA indoor unit display: Outdoor ambient temperature sensor (T4) open or short circuit
multi-zone outdoor unit display: Zone A indoor coil outlet sensor (T2B) fault, shown on the outdoor display
FaultDIY checks
F2MPA / MPB / MLA indoor unit display: Condenser coil temperature sensor (T3) open or short circuit
multi-zone outdoor unit display: Zone B indoor coil outlet sensor (T2B) fault, shown on the outdoor display
FaultDIY checks
F3MPA / MPB / MLA indoor unit display: Compressor discharge temperature sensor (TP) open or short circuit
multi-zone outdoor unit display: Zone C indoor coil outlet sensor (T2B) fault, shown on the outdoor display
FaultDIY checks
F4MPA / MPB / MLA indoor unit display: Outdoor unit EEPROM parameter error
multi-zone outdoor unit display: Zone D indoor coil outlet sensor (T2B) fault, shown on the outdoor display
FaultTechnician
F5MPA / MPB / MLA indoor unit display: Outdoor fan speed out of control (outdoor fan motor fault)
multi-zone outdoor unit display: Zone E indoor coil outlet sensor (T2B) fault, shown on the outdoor display
FaultDIY checks
P0Inverter module (IPM) malfunctionProtectionTechnician
P1MPA / MPB / MLA indoor unit display: Over-voltage or under-voltage protection
multi-zone outdoor unit display: High pressure protection (outdoor display)
ProtectionDIY checks
P2MPA / MPB / MLA indoor unit display: High temperature protection (compressor top or inverter module)
multi-zone outdoor unit display: Low pressure protection (outdoor display)
ProtectionDIY checks
P3MPA / MPB / MLA indoor unit display: Outdoor temperature too low protection (heating lockout)
multi-zone outdoor unit display: Compressor current overload protection (outdoor display)
ProtectionDIY
P4MPA / MPB / MLA indoor unit display: Inverter compressor drive error
multi-zone outdoor unit display: Compressor discharge temperature protection (outdoor display)
ProtectionTechnician
P5MPA / MPB / MLA indoor unit display: Mode conflict (multi-zone)
multi-zone outdoor unit display: Condenser high temperature protection (outdoor display)
ProtectionDIY
P6MPA / MPB / MLA indoor unit display: Outdoor low pressure protection
multi-zone outdoor unit display: Inverter module (IPM) malfunction (outdoor display)
ProtectionDIY checks
dFDefrost cycle runningStatusDIY
CLFilter cleaning reminderStatusDIY
APWi-Fi pairing (access point) modeStatusDIY
EH 00Indoor unit EEPROM parameter errorFaultDIY checks
EL 01Communication error between indoor and outdoor unitsFaultDIY checks
EH 02Zero-crossing signal detection errorFaultDIY checks
EH 03Indoor fan speed out of controlFaultDIY checks
EH 60Indoor room temperature sensor (T1) open or short circuitFaultDIY checks
EH 61Evaporator coil temperature sensor (T2) open or short circuitFaultDIY checks
EL 0CRefrigerant leak detected (low charge)FaultDIY checks
EH 0AIndoor unit EEPROM parameter errorFaultDIY checks
EH 0bCommunication error between indoor main board and display boardFaultDIY checks
EC 51Outdoor unit EEPROM parameter errorFaultTechnician
EC 52Condenser coil temperature sensor (T3) open or short circuitFaultDIY checks
EC 53Outdoor ambient temperature sensor (T4) open or short circuitFaultDIY checks
EC 54Compressor discharge temperature sensor (TP) open or short circuitFaultDIY checks
EC 56Coil outlet temperature sensor (T2B) open or short circuitFaultDIY checks
EC 07Outdoor fan speed out of controlFaultDIY checks
PC 00Inverter module (IPM) malfunctionProtectionTechnician
PC 01Over-voltage or under-voltage protectionProtectionDIY checks
PC 02Compressor top temperature (overload) protectionProtectionDIY checks
PC 03Pressure protection (high or low pressure switch)ProtectionDIY checks
PC 04Inverter compressor drive errorProtectionTechnician
PC 08Outdoor over-current protectionProtectionDIY checks
PC 0ACondenser high temperature protectionProtectionDIY checks
PC 0FPFC module malfunctionProtectionTechnician
PC 40Communication error between outdoor main board and inverter boardFaultTechnician
PC 43Compressor missing phase (lack of phase) protectionProtectionTechnician
PC 44Compressor zero-speed protectionProtectionTechnician
PC 46Compressor speed out of controlProtectionTechnician
PC 49Compressor over-current (phase current) protectionProtectionTechnician
FPLow-temperature heating hold (46°F freeze-protection mode)StatusDIY
FCForced cooling test modeStatusDIY
LLRemote or wired controller lockedStatusDIY
cFAnti-cold-air (heating warm-up)StatusDIY
CPRemote on/off contact openStatusDIY
E6PFC module protection (outdoor display)ProtectionTechnician
E8Outdoor fan speed fault (outdoor display)FaultDIY checks
F6Zone F indoor coil outlet sensor (T2B) fault, shown on the outdoor displayFaultDIY checks

How Lennox shows error codes

MPA / MPB / MLA indoor unit display: The code appears on the indoor unit's LED display in place of the set temperature. Some models also blink the indicator lamps in a pattern that matches the code. E codes are faults in the indoor unit or its communication link, F codes are faults on the outdoor side, and P codes are protections: the outdoor unit has stopped itself to prevent damage. EC is the refrigerant leak check.

MCB / MWCB indoor unit display: The display shows a two-letter prefix and a two-character suffix, either together (EH60) or alternating (EH, then 60). Write both parts down; the suffix is what identifies the fault. EH and EL are indoor-side faults, EC is an outdoor-side fault, and PC is an outdoor protection: the unit stopped itself to prevent damage.

multi-zone outdoor unit display: These codes appear on the small LED display on the multi-zone OUTDOOR unit's control board (behind the service panel, or visible through a window on some models). The indoor units show their own, different codes for the same fault, so check which display you are reading. On the outdoor display, E codes are outdoor faults, F codes identify which zone's coil sensor failed (F1 = zone A, F2 = zone B, and so on), and P codes are protections.

Brands built on the same platform

These brands share a code table with Lennox because the same factory builds them, so their pages describe the same faults: ACiQ, AirEase, Arcoaire, Arctic King, Armstrong Air, Blueridge, Bosch, Bryant, Carrier, Comfortmaker, Concord, Day & Night, Della, Ducane.

Sources

  • Lennox Corp1816-L7 Mini-Split Systems Service Manual: Indoor and Outdoor Unit Error Codes (MPA/MPB/MLA, MWMA, MCFA, MMDA), 10/2020
  • Lennox MCB / MWCB Mini-Split Service Manual (error code table 2.1)

Updated September 2026. Manufacturer site: www.lennox.com