Mitsubishi: Indoor Coil / Intake Thermistor Fault

What this fault means

An indoor temperature thermistor (room intake or pipe sensor) is reading out of range, so the system cannot control capacity correctly. Often a P1/P2-type code on Mitsubishi units.

Likely causes

• Failed or disconnected thermistor
• Damaged sensor wiring
• Indoor control board fault

What you can safely check

• Replace a dirty air filter — restricted airflow causes a surprising share of furnace faults.
• Confirm registers and the outdoor unit are clear of snow, leaves and debris.
• Cycle power at the switch once and let the system retry.

Related Mitsubishi faults