Mitsubishi Electric AC Error Code E1 — Indoor PCB Fault

What Does This Error Mean?

E1 on a Mitsubishi Electric AC indicates a fault with the indoor unit PCB (printed circuit board — the main control board). This board controls everything the indoor unit does — fan speed, temperature sensing, and communication with the outdoor unit. E1 almost always requires a technician; the board may need replacement.

Affected Models

Mitsubishi Electric MSZ-AP Series
Mitsubishi Electric MSZ-EF Series
Mitsubishi Electric MSZ-GL Series
Mitsubishi Electric MSY Series
Mitsubishi Electric Inverter Split AC (all models)

Common Causes

Indoor PCB component failure — voltage regulator, relay, or control chip has failed
Power surge or voltage spike causing PCB damage
Moisture or water ingress onto the indoor PCB
Loose connector or wiring harness at the indoor PCB
Manufacturing defect on units within warranty period

How to Fix It

Turn the AC off at the remote, then switch off the circuit breaker.

Wait 5 minutes, restore power, and attempt one restart. Occasionally a power surge causes a temporary PCB lockout that clears on power cycle.
Do not continue restarting if E1 returns.

Repeated restart attempts on a faulty PCB can cause additional component damage.
Check whether the unit is still within warranty.

Mitsubishi Electric typically offers a 5-year warranty on indoor units in many markets. If the unit is within warranty, a PCB replacement may be fully covered — contact your dealer or Mitsubishi Electric directly.
Book an authorised Mitsubishi Electric service visit.

Provide the technician with the model number (found on the label inside the front panel) and the exact error code displayed.

When to Call a Professional

E1 requires a Mitsubishi Electric authorised technician. PCB diagnosis and replacement must be performed by a trained professional — the board handles mains voltage and requires correct handling to avoid further damage.

Frequently Asked Questions

How much does a Mitsubishi Electric indoor PCB replacement cost?

A Mitsubishi Electric indoor PCB typically costs $80–250 for the part, plus technician labour of $60–150. If the unit is under warranty, this is often fully covered. Always get a written quote before approving any board replacement.

Can a power surge cause E1?

Yes — voltage spikes from lightning, grid fluctuations, or large appliances switching on can damage the sensitive components on the indoor PCB. Using a voltage stabiliser or surge protector on the AC circuit can prevent this type of damage.