Fault Code Lookup

HVAC Sales Master

E155

Refrigerant leak detector sensor #2 communication lost

This code typically points to

Harness or connector issue on sensor #2

Next checks to confirm

Inspect sensor #2 wiring and connector
Retest with Low GWP test button

Escalation

Blower latches for a minimum of 5 minutes

Reset behavior

Clears when communication is reestablished; blower remains latched for at least 5 minutes regardless.

Safety Critical

Immediate concern

⚠ Cross-generation conflict

Codes E150, E151, E152, E154, E155, E160, E161, E163, E164, and E390 only exist on K-revision Lennox furnaces (EL195UHNEK, ML196UHEK). These are refrigerant leak detection codes for R-454B A2L compliance. E154/E155 will latch the blower ON for at least 5 minutes regardless of thermostat call — this is a code-mandated safety behavior. A2L refrigerant detection CANNOT be disabled — it's prohibited by safety codes.

Source

Lennox EL195UHNEK Installation Instructions 508575-01, p.46

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