Fault Code Lookup

HVAC Sales Master

51-01

Outdoor air temperature (OAT) sensor open

This code typically points to

Failed OAT thermistor
Broken sensor wire
Poor connection at board

Next checks to confirm

Measure OAT sensor resistance
Verify wiring continuity to board

Escalation

Replace sensor after wiring confirmed good.

Reset behavior

Clears when sensor reading returns to valid range.

Service Soon

Schedule repair

Need deeper detail?

Retrieve the subcode for this platform:

From the main screen, touch Menu
Touch and hold the Service icon for at least 10 seconds until it turns green
Open Service Information
Use View Diagnostics for the most recent fault's top three likely root causes
Use Last 10 System Events for timestamped recent events
Use Run/Fault History for resettable fault counters, cycle counters, and run times

Source

Carrier inverter/Connex service manual event tables

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