Bosch furnace error 4e

A common error message for the Bosch furnace is E4:

Bosch furnace error 4e

Bosch furnace fan Error

Bosch furnace error 4e occurs when you try to start the heating system.

The error code 4E, also called “no combustion” or “NOx/CO2 sensor fault,” is generated if there is a faulty CO2 sensor circuit in the furnace. The most common cause of this error code is that the wall thermostat has changed settings and no longer controls the required fuel input, despite being programmed to do so.

Bosch furnaces have been upgraded for smarter performance for your comfort and protection, including improving CO2 sensor reaction time and optimizing motor operation according to input from humidity sensors.

Bosch has been producing quality furnaces since 1934. The company has built a reputation for consistently developing innovative, reliable, and efficient heating appliances that work well with your home’s design.

The Bosch 4e Error is an error code that is seen on the displays of some Bosch furnaces when their circuits are overloaded. This can happen if you have too many people in the house or use the furnace for an extended period.

This error will be fixed by replacing the furnace control board; however, it does not affect the functioning of the appliance in any way (including safety).