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Error code reference
Honeywell Water Heater Error Codes
8 error codes documented with diagnostic procedures.
Have your model number? Get codes specific to your unit.
0 FlashesControl is off or pilot is out.1 FlashNormal operation (bright/dim heartbeat).2 FlashesThermopile voltage is low.4 FlashesTemperature exceeded (ECO activated).5 FlashesSensor failure.7 FlashesInternal control failure.8 FlashesPower off failure.Status Light On (solid)Pilot light was recently extinguished and the thermopile is cooling down.
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Step-by-step tests, expected values, wiring diagram references, and verified part numbers.
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More Honeywell error codes
Common questions
How do I find the error code on my Honeywell Water Heater?
Most Honeywell water heaters show the code directly on the control panel display. If your model has no display, it can be read by entering diagnostic mode with the key sequence for your model. The full procedures include model-specific instructions for reading codes.
Are these codes specific to my model?
The codes here apply broadly to Honeywell water heaters. Meanings and diagnostic steps can vary by model and production year, so enter your model number for model-specific information and procedures.
What do I do if my code is not listed?
Some codes are model-specific or only appear in diagnostic mode. Enter your model number to get codes specific to your unit, or contact us. We update the database continuously from manufacturer service documentation.
How much does it cost to access the full diagnostic procedures?
A 3-day pass is $9.95 one-time and gives full access to all brands, codes, and procedures. Monthly access is $29/month with unlimited access to everything including Max AI diagnostics.