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0004

Error code 0004 — High temperature protection

Lennox · Appliance Systems

What does 0004 mean?

A critical error has occurred related to the system's high temperature protection. A pop-up screen will appear indicating this condition. The error code is displayed as 0004. This notification is critical and may require dealer assistance.

Common Causes

  • System is overheating
  • Faulty temperature sensor

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Press the back button to dismiss the pop-up notification.

  2. 2

    Contact your dealer to resolve the issue.

  3. 3

    Check system for obvious obstructions or issues.

  4. 4

    Ensure proper airflow around the unit.

Browse all codes in this manual (8)
Verified technical data. Last updated: April 2026

Related Faults

Schedule hold permanentlySchedule hold permanently — Schedule overridden indefinitelySchedule hold until next periodSchedule hold until next period — Schedule temporarily overriddenblue flamesBlue flames icon — System is cooling
Source: Lennox Appliance Systems
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