Indoor unit stops shortly after starting, E2 displayed or timer LED flashes E2 pattern

Safety first: Isolate power at the breaker before removing the indoor unit cover. Thermistors are low-voltage but are connected to live circuits.

• Access the thermistor: Remove the front panel and air filters. The room temperature thermistor is usually clipped near the indoor coil inlet or in the return air stream, connected by thin wires to the PCB.
• Check connection: Ensure the thermistor plug is fully seated on the indoor PCB. Reseat it to clear any oxidation.
• Inspect the sensor: Look for broken wires, damaged insulation, or a sensor that has fallen out of its clip. Re-clip it in the correct position if it has moved.
• Basic resistance check (for skilled users): With power off and the thermistor unplugged, measure resistance with a multimeter. At room temperature (~25°C), Fujitsu NTC thermistors are typically around 10kΩ (check service manual for exact value). Infinite or near-zero resistance indicates a bad sensor.
• Replace if faulty: If the thermistor is open/shorted or physically damaged, replace it with a Fujitsu-compatible room thermistor. Route the new sensor wires away from high-voltage lines.
• PCB suspicion: If a known-good thermistor still triggers E2, the indoor PCB sensor circuit may be defective and should be replaced by a technician.