Error Code Code 43
Carrier 58MVP Error Code Code 43: Pressure Switch Calibration Fault
TL;DR
Indicates the low and high pressure switch make points during high-heat purge are not within the calibration range. This is determined by reading inducer motor RPM when low-pressure switch LPS and high-pressure switch HPS make. The furnace control board flashes Fault Code 43, shuts unit down (inducer runs for 15 sec), waits 2 minutes, stops flashing the fault code, and restarts the heating cycle. Most likely cause: plugged condensate drain. 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 Code 43 Mean?
Indicates the low and high pressure switch make points during high-heat purge are not within the calibration range. This is determined by reading inducer motor RPM when low-pressure switch LPS and high-pressure switch HPS make. The furnace control board flashes Fault Code 43, shuts unit down (inducer runs for 15 sec), waits 2 minutes, stops flashing the fault code, and restarts the heating cycle.
Common Causes
When to Call a Professional
Contact a licensed HVAC technician if:
- Basic troubleshooting did not resolve the error
- You smell gas at any point during the process
- You are not comfortable working around gas lines or electrical components
- The unit needs a gas valve, control board, or motor replacement