Lennox Split & Multi-Split

Lennox Split & Multi-Split Error Code 51

Split & Multi-Split: Heat pump (outdoor)

What It Means

  • High pressure sensor malfunction

Causes & actions from Lennox

How it shows
  • el18kslv outdoor fault display: 51
  • el18kslv pcb fault led: 51

Continuous detection of AD value below 11 or above 1012 for 30 seconds

Applicable models & manual sources
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.

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