Fault Code E06-after-warmup – Mitsubishi Electric Series Pro 2

Meaning: A communication fault was detected between modules or boards. This page focuses on cases where the code appears after warm-up.

Common causes

• Loose or damaged wiring/connector
• Connector corrosion, moisture intrusion, or contamination
• Out-of-range operating conditions
• Component wear or intermittent failure
• Improper installation or setup
• Communication wiring mismatch
• Voltage drop during compressor start
• Thermal expansion causing intermittent connection
• Heat-related sensor drift
• Short circuit or internal module failure

What to check first

1. Power down the unit before inspection and allow it to cool (if hot)
2. Turn power off at the disconnect before inspecting indoor/outdoor communication wiring
3. Verify connectors are seated and wiring is intact (no pinches/cuts/burn marks)
4. Confirm supply power is within specification for your unit
5. Remove debris and ensure proper ventilation/airflow
6. After correcting the suspected cause, power-cycle and retest
7. Check for terminal corrosion and tighten connections to manufacturer torque guidance
8. If the issue occurs after warm-up, look for heat-related wiring/sensor issues

Is it safe to keep running?

No. Stop operation and troubleshoot before continuing.

Reset guidance

After correcting the underlying issue, clear the fault by power-cycling the unit, then retest after warm-up. If the code returns, stop and escalate to service diagnostics.

When to call service

• The code returns immediately after basic checks
• There are visible signs of damage, overheating, or burning odor
• The unit will not start or shuts down repeatedly
• You are not comfortable performing electrical diagnostics safely

General reference only. Not affiliated with manufacturers. Meanings describe common patterns and may vary by exact model/version—always confirm with your model’s service manual.