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E7

E7 — Indoor unit EEPROM error (MMDB Indoor Units)

Lennox · Air Conditioning

What does E7 mean?

This error code indicates a problem with the indoor unit's EEPROM on specific MMDB models. The EEPROM stores essential operating data.

Common Causes

  • Data corruption in the EEPROM
  • Failure of the EEPROM chip
  • Power surge or interruption

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the unit has a stable power supply.

  2. 2

    Perform a power reset: turn off the breaker for 30 seconds, then turn it back on.

  3. 3

    If the error persists, the indoor unit's control board may require replacement.

Browse all codes in this manual (57)
Verified technical data. Last updated: April 2026

Related Faults

E0E0 — Indoor unit EEPROM error (MMDB Indoor Units)E1E1 — Communication error between indoor and outdoor units (MMDB Indoor Units)E3E3 — Indoor fan speed error (MMDB Indoor Units)
Source: Lennox Air Conditioning
Open Manual (Page 6)Search more codes in this manual