Bosch Temperature Sensor Short Circuit

Furnace shows F1; may indicate sensor short circuit

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

Shorted NTC sensor (flow, return, or DHW), Sensor wiring shorted to chassis, Incorrect sensor type installed

Safety: Turn off power.

Identify sensor: Consult the Bosch service manual to see which sensor F1 refers to on your model.
Disconnect sensor: Remove the suspect sensor from the board and measure resistance. A reading near 0 Ω indicates a short; replace the sensor.
Inspect cable: Look for crushed or pinched sections where the insulation may be damaged and touching metal.

Medium 3/5

Temperature Sensor (NTC)

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