Code 23 — Furnace LPS or HPS Closed

What does 23 mean?

This fault on a furnace indicates that either the Low Pressure Switch (LPS) or High Pressure Switch (HPS) is closed when it shouldn't be. This suggests an issue with refrigerant pressure or sensor readings.

• Incorrect pressure readings from sensors
• Sensor malfunction
• Refrigerant issues (overcharge/undercharge) in systems with cooling components
• Wiring fault to the pressure switches

Click steps to track your progress.

1. 1

   Turn off the power to the furnace at the circuit breaker for 30 seconds to reset.

2. 2

   Verify that all air filters are clean and air vents are open.

3. 3

   Ensure the outdoor unit (if applicable) is free from debris and has clear airflow.

4. 4

   If the problem persists, contact a qualified HVAC technician for diagnosis, as it may involve refrigerant pressures.