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A001

A001 - Ignition lockout

Rheem · Water Heaters

What does A001 mean?

The heater has failed to ignite 9 times consecutively. The heater is disabled.

Common Causes

  • Failed ignition attempts

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn the unit off and then on again to clear the error code.

  2. 2

    If the problem persists, contact technical support or a service provider.

Browse all codes in this manual (70)
Verified technical data. Last updated: April 2026

Related Faults

1111 - Gas shut-off valve is not fully open1212 - Gas service interrupted or LP gas low13Hot and cold water lines reversed
Source: Rheem Water Heaters
Open Manual (Page 42)Search more codes in this manual