2503 (P4) Drain sensor trouble

What does 2503 (P4) mean?

This error indicates a problem with the drain sensor, which monitors the water level in the condensate drain pan. A faulty sensor might lead to the system incorrectly detecting an overflow or not detecting one when it occurs.

• Defective drain sensor.
• Loose or disconnected wiring to the drain sensor.
• Debris interfering with the sensor's operation.
• Malfunction of the input circuit on the indoor unit's board.

Click steps to track your progress.

1. 1

   Turn off the power to the indoor unit at the circuit breaker.

2. 2

   Locate the drain sensor (often near the drain pan) and check its wiring connections for looseness or damage.

3. 3

   Ensure the drain pan and sensor area are clean and free of any debris that might interfere with sensor operation.

4. 4

   Restore power to the unit. If the error persists, contact a qualified technician.

5. 5

   A technician will need to test the drain sensor and potentially the indoor unit's control board.