Boiler displays E03; commonly related to flue or exhaust sensor on some Laars models.

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

Failed flue sensor, Loose sensor wiring, Overheating due to poor flow or vent blockage, Control board sensor circuit fault

Safety first: High flue temperatures are hazardous. Turn off power and gas if vent damage is suspected.

Inspect flue sensor: Locate the flue sensor on the exhaust outlet. Ensure it is firmly attached and wiring is intact.
Check venting: Look for blockages or damage in the vent system.
Reset and monitor: After cooling, reset the boiler and observe. If E03 recurs, stop using the boiler.

When to call a professional: A technician should test the sensor and evaluate combustion and venting.

Hard 4/5

Flue Temperature Sensor

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