Carrier 58MVC Error Code 25: Model Selection or Setup Error
What Does Code 25 Mean?
Status code 25 on the Carrier 58MVC signals that the control board cannot properly identify the furnace model or has detected incorrect setup switch positions. The 58MVC uses a model plug (PL4) that tells the control board which specific furnace model it is installed in, and setup switches (SW1-1 and SW1-6) that configure operating parameters.
If this code flashes only four times at power-up, it means the control is using model selection data stored in memory as a fallback. If the code flashes continuously, the board cannot determine the correct configuration at all. This situation most commonly occurs after a control board replacement when the installer forgets to transfer the model plug, or when setup switches are inadvertently changed during service work.
The furnace may still attempt to operate using default settings, but it will not run optimally or safely without the correct configuration. An HVAC technician needs to verify the model plug is installed and correct, confirm the setup switch positions match the installation requirements, and ensure the control board software version is compatible with the model plug being used.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Model plug (PL4) missing or incorrect | Most common | ✗ Call a pro → |
| Setup switch SW1-1 or SW1-6 positioned improperly | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- When this code appears — the model plug and setup switch configuration require a technician familiar with the 58MVC control board
✓ Verified against manufacturer service manual — March 2026