p8
Moderate
Mitsubishi Electric · Mini-Splits & Ductless Systems
Pipe Temperature Abnormality
Quick Answer
Error code P8 on your Mitsubishi Electric Mini-Splits & Ductless Systems means: Pipe Temperature Abnormality. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
  1. Refrigerant pipe temperature reading is outside the expected range during operation
  2. Low or high refrigerant charge
  3. Metering device (expansion valve) not regulating properly
  4. Thermistor partially failed giving intermittently inaccurate readings
How to Fix It
1
Verify the pipe thermistor reading matches an independently measured pipe surface temperature
2
Check refrigerant pressures and compare to expected operating conditions
3
Inspect the expansion valve for proper operation by checking superheat values
4
Replace the pipe thermistor if readings do not match actual pipe temperature
5
A licensed HVAC technician should diagnose if refrigerant charge or expansion valve is the root cause
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Pipe thermistor
Electronic expansion valve
Refrigerant (R-410A)
Related Error Codes
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