Furnace intermittently locks out with E17, often during high demand or hot weather.

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Blocked flue or restricted airflow, Faulty flue gas temperature sensor, Incorrect flue length or configuration, Over-firing due to gas valve misadjustment

How to Fix / Troubleshooting

Safety: Overheated flue gases can be dangerous. Do not continue resetting the furnace repeatedly.

User checks:

Ensure the flue terminal is clear and not covered or boxed in.

Technician checks:

Measure flue gas temperature and compare with design values.
Test the flue gas temperature sensor resistance and replace if out of range.
Inspect flue for partial blockages or incorrect installation.
Check and adjust gas rate and combustion settings.

Repair Difficulty

Professional Required 5/5

Required Part

Flue Gas Temperature Sensor

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