P5

Drain Overflow Protection Malfunction

Mitsubishi Electric · R410A Systems

What does P5 mean?

The mechanism designed to prevent drain pan overflow in the indoor unit is not functioning correctly. This could be due to a faulty drain sensor, a malfunctioning condensate pump, or a clogged drain line, leading to water damage.

Common Causes

  • Drain overflow protection activated.
  • Drain pan is full and cannot remove water.
  • Clogged condensate drain line.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the drain sensor (P4) is operating correctly by checking its resistance or output.

  2. 2

    Inspect the condensate drain line for blockages, kinks, or improper slope that could impede water flow.

  3. 3

    If a condensate pump is installed, verify its operation and check its float switch for proper activation and deactivation.

Browse all codes in this manual (60)
Verified technical data. Last updated: March 2026

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Source: Mitsubishi Electric R410A Systems