Mitsubishi P2: the pipe sensor that tells defrost and freeze control what to do

What Does Error P2 Mean?

P2 identifies an abnormality in the indoor pipe temperature thermistor, the sensor clamped to the indoor heat exchanger rather than the one reading room air. Its value drives freeze protection in cooling and heat-exchanger temperature logic in heating, so the control stops rather than run those functions blind. Applies to: Mitsubishi Electric indoor units publishing the P-series fault table, including M-Series wall units and Mr Slim indoor equipment The entry read here belongs to Mitsubishi Electric indoor units that publish the P-series table. Some Mitsubishi indoor units carry more than one pipe thermistor, and the table then separates them by code, so the position of the failed sensor comes from the service manual for that exact indoor model rather than from the code alone. Owner-safe checks: Switch the affected indoor unit to fan only if the coil has visible frost, and let it thaw without heat, tools, or water. | Note the indoor address, the room, and whether other heads on the same system continue to work normally. | Write down any period in the preceding weeks when heating airflow was slow to start or cooling produced indoor frost. Qualified technician: Verifying sensor mounting, measuring thermistor resistance against the published curve, and inspecting the indoor harness all need the indoor casing opened by a qualified technician. | Repeated indoor coil frosting alongside P2 needs refrigerant and airflow assessment, which is licensed work and not an owner task.