Error Code Status Code 25

Carrier 58MVC Error Code Status Code 25: Model Selection or Setup Error

TL;DR
Status code 25 on your Carrier 58MVC indicates a model selection or setup error. The most common cause is a DIP switch (SW1-1 or SW1-6) accidentally left in the ON position. Both should be OFF during normal operation.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code Status Code 25 Mean?

Code 25 means the furnace control board has detected a configuration problem. The 58MVC uses a combination of a model plug (PL4) and DIP switches to identify the furnace model and configure its operating parameters. When the control detects a mismatch or missing configuration, it displays code 25.

The most common cause is surprisingly simple: the setup switches SW1-1 or SW1-6 were left in the ON position. SW1-1 is the "stored code clear/display" switch used during troubleshooting, and SW1-6 is the "component test" switch used during installation. Both must be in the OFF position during normal furnace operation. If a technician recently serviced the furnace, they may have forgotten to flip these switches back.

Less commonly, code 25 can indicate that the model identification plug (PL4) is missing, installed in the wrong position, or has become loose. This plug tells the control board which specific 58MVC model it is controlling. In rare cases with twinned (paired) furnaces, mismatched models can also trigger this code.

Common Causes

Cause Likelihood DIY?
Setup switch SW1-1 or SW1-6 left in ON position ✓ DIY fix →
Model plug PL4 missing or incorrect ✗ Call a pro →
Two different furnace models twinned incorrectly ✗ Call a pro →

How to Fix It: Check DIP Switch Positions

âš  Safety First
Always turn off the furnace at the power switch or breaker and shut off the gas supply before beginning. Do not proceed if you smell gas — leave the area and call your gas company immediately.

What You'll Need

Steps

  1. Turn off power at the breaker or power switch AND shut off the gas supply Locate the furnace circuit breaker and turn it OFF. Find the gas shutoff valve on the supply line to the furnace and turn it to the closed position (perpendicular to the pipe). If you smell gas, leave immediately and call your gas company.
  2. Remove the blower access panel to access the control board Remove the lower blower access panel on the furnace. The control board with the DIP switches is visible inside. Use a flashlight to locate the row of small DIP switches labeled SW1.
  3. Verify SW1-1 and SW1-6 are in the OFF position Look at switches SW1-1 and SW1-6 on the DIP switch block. During normal operation, both must be in the OFF position (typically down). If either is in the ON position (up), use a small flathead screwdriver or your fingernail to slide it to OFF. Do not change any other switch positions.
  4. Restore power and gas, then verify Replace the blower access panel (the door switch must be engaged for the furnace to operate). Turn the gas supply valve back to the open position. Turn the breaker back ON. The control board should reset and the amber LED should show a normal status.
How to Verify
After restoring power, check that the amber LED shows a steady ON (standby) or begins a normal ignition sequence when the thermostat calls for heat. If code 25 persists after confirming both DIP switches are OFF, the model plug PL4 may be the issue — this requires a technician.

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Carrier 58MVC Series 100 Troubleshooting Guide, p.8