Carrier Furnace Code 25
WarningShown as: 2 short flashes, 5 long flashes
Model selection or setup error. The model plug (PL4) is missing or wrong, or a setup switch is in the wrong position. If the code flashes only 4 times at power-up, the control is running on the model selection stored in memory.
Manual wording: “25 MODEL SELECTION OR SETUP ERROR - Either Indicates the model plug (PL4) is missing or incorrect or setup switch "SW1-1" or "SW1-6" is positioned improperly.”
Documented for: 58MVP, 58UVB and other variable-speed two-stage Carrier furnaces
Likely causes, most common first
- Model plug PL4 missing or incorrect (common after a replacement control board)
- Setup switch SW1-1 or SW1-6 left ON
- Two different furnace models twinned together
When to call a technician
This is a setup fault that appears after service work. The technician who last worked on the furnace needs to install the correct model plug and reset the setup switches.
A Carrier furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Troubleshooting Guide - Variable Speed, Two-Stage Gas Furnaces (Form 58-06T) (Carrier, 58MVP, 58UVB and other Carrier variable-speed two-stage gas furnaces (replaces 58MVP-10SM)) · checked 2026-08-25