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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

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: April 2026

Related Faults

E0Transmitting/Receiving Signal ErrorE112Auto Addressing Conflict / Factory Address Setting ErrorE14Master/Slave System Configuration Error
Source: Mitsubishi Electric R410A Systems
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