Fault Code Lookup

HVAC Sales Master

E164

Low GWP Test mode active

This code typically points to

Manual activation of Low GWP test button

Next checks to confirm

Confirm code was intentionally invoked as a test function

Escalation

Test mode only

Reset behavior

Automatically clears after 1 minute.

Informational

No action needed

⚠ 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.47

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