What it means
Mitsubishi's installation manuals word it "Outdoor unit receives no signal from indoor unit." The PUZ-WM outdoor unit service manual calls E9 an indoor/outdoor unit communication error (transmitting error) at the outdoor unit.
What to check, in order
- Check both units are switched on
This is Mitsubishi's first action. Make sure the indoor unit and the outdoor unit both have power, including the outdoor unit's isolator and breaker.
- Switch off and on again
Turn both units off at their main switches and back on straight away.
- Write the code down if it returns
Make a note of the code and contact your installer.
When to call your installer
Call your installer. Mitsubishi says to check the connecting cable for damage or loose connections and refers engineers to the outdoor unit service manual.
Quick answers
What does the Mitsubishi Ecodan E9 error code mean?
The outdoor unit isn't receiving signals from the indoor unit, so the two can't work together. Mitsubishi's installation manuals word it "Outdoor unit receives no signal from indoor unit." The PUZ-WM outdoor unit service manual calls E9 an indoor/outdoor unit communication error (transmitting error) at the outdoor unit.
Can I fix Mitsubishi Ecodan E9 myself?
Easy (about 10 minutes). Start with: check both units are switched on; switch off and on again; write the code down if it returns. Call your installer. Mitsubishi says to check the connecting cable for damage or loose connections and refers engineers to the outdoor unit service manual.
Is Mitsubishi Ecodan E9 worth repairing?
Worth fixing. Free if a unit had been switched off. Otherwise an installer needs to trace the connection between the units.
Checked against
- Ecodan FTC5 Hydrobox Installation Manual, EHS(D)(C)-MEC / EHPX-VM2C (RG79D954H05) (PDF)
- Ecodan Hydrobox EHSC/EHSD series (D models) Installation Manual, error code table (manualslib copy)
- Ecodan Hydrobox EHSD/ERSD series (E models) Installation Manual DG79T728H01, error code table (manualslib copy)
- Ecodan PUZ-WM(50-60-85-112) Outdoor Unit Service Manual (OCH727A) (PDF)
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.