fb
Moderate
Mitsubishi Electric · Mini-Splits & Ductless Systems
Outdoor Control Board Fault
Quick Answer
Error code Fb on your Mitsubishi Electric Mini-Splits & Ductless Systems means: Outdoor Control Board Fault. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Power cycle the system at the breaker for 60 seconds and restore power
2
Inspect the outdoor PCB for visible signs of damage (burn marks, swollen capacitors, corrosion)
3
Check the electrical compartment for signs of moisture or water intrusion
4
Verify input voltage to the outdoor unit is within rated specifications
5
Outdoor PCB replacement should be performed by a Mitsubishi Diamond Contractor or licensed HVAC technician
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
Outdoor PCB
Inverter board
Electrical compartment seal/gasket
Related Error Codes