Mitsubishi Air Conditioner Error E4
⚡ Quick Answer: The Mitsubishi Air Conditioner E4 error indicates a communication failure between the indoor and outdoor units. This may manifest as the E4 error code... ✅ DIY Fixable
What Does Error E4 Mean?
The Mitsubishi Air Conditioner E4 error indicates a communication failure between the indoor and outdoor units. This may manifest as the E4 error code appearing on the display, with the air conditioner becoming unresponsive or intermittently responding to remote commands. The issue is often related to remote controller signal errors, loose wiring, or faulty remote hardware.
Common Symptoms:
- Error E4 displayed on indoor unit or remote display
- Air conditioner unresponsive or intermittently responsive to remote commands
- Remote control operations ineffective
Possible Causes
- Remote controller communication or signal receiving error between remote and indoor unit (high)
- Disconnected, loose or incorrectly wired remote control signal line (medium)
- Faulty remote controller hardware (medium)
How to Fix Error E4
DIY Fix Basic Remote Communication Checks
- Turn off and restart the air conditioner to attempt clearing transient communication faults
- Check that the remote control has batteries installed correctly and functioning
- Ensure nothing is obstructing the line of sight if using IR communication
- Observe whether the remote operations reliably result in unit responses
Technician Only Inspect and Repair Remote Wiring and Communication
- Shut off power to the air conditioner and inspect remote transmission wiring at both indoor unit and remote terminals
- Verify wiring meets manufacturer specification (two-core cable, correct gauge, no shielding unless specified) and that terminations are secure
- Test the remote controller hardware and replace if necessary
- Check indoor unit signal receiving circuitry and replace control board components if defective
Parts needed: Remote controller unit, Remote signal cable, Indoor unit control board/receiver
- If the error persists after basic remote checks and cable inspection
- If there is any sign of damaged internal wiring or control board components
- If you are unsure about safely accessing internal unit wiring
Next step
Choose the next step for E4
Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.
Most relevant component to inspect
HVAC Control Board
Controls fan, compressor, sensor, and communication functions in the HVAC unit.
- Typical part-only price
- $90 - $320
- DIY difficulty
- Hard
- Estimated time
- 45-120 mins
Where can I find the model number?
Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.
Verify the complete model and part number on the retailer's compatibility page before ordering.
Other parts options
Check related components first; use model search as a fallback.
Model-compatible Air Conditioner parts
Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. We may earn a commission from other qualifying purchases or service requests made through links on this page, at no additional cost to you. Recommendations are based on repair relevance, not commission rate.
Optional routine care
Maintenance supplies
These products support cleaning or routine upkeep. They are separate from the possible repair components above and are not claimed to fix this error code or symptom.
Air Conditioner Fin Cleaner
For routine cleaning of accessible coil fins when permitted by the manufacturer. Disconnect power and follow product and appliance instructions.
Model-Compatible Washable AC Filter
A reusable filter option only where the appliance supports one. Match the full model, dimensions, and filter specification.
Compatibility check required: use the complete appliance model and compare the existing filter, bag, or specification before ordering.
Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. Recommendations are based on routine-care relevance, not commission rate.
Technical Specifications
| wattage | N/A |
|---|---|
| component | Control Board |
| resistance | N/A |
| part_number | Mitsubishi 938D100A20 |
| voltage_rating | 230V AC |
Common Questions
What does E4 error mean on Mitsubishi Air Conditioner?
E4 error indicates a communication failure between indoor and outdoor units, often making the air conditioner unresponsive.
Can I fix Mitsubishi Air Conditioner E4 error myself?
Yes, you can check the remote batteries, restart the unit, and ensure there are no obstructions.
How much does it cost to fix E4 error?
Repair costs typically range from $80 to $350, depending on parts and diagnostic time.
When should I call a technician for E4?
Call a technician if the error persists after basic checks or if there's visible damage to internal components.
Sources & References
- Mitsubishi Electric AC Fault Code E4 Explained (community)
Data last verified: 2026-07-22
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