Bosch Dryer Error Code 2

Error code 2 on a Bosch dryer indicates a fault with NTC thermistor R3, which is the exhaust-air temperature sensor. The dryer signals this fault by flashing the 'Iron dry' LED in the progress indicator. The NTC (Negative Temperature Coefficient) thermistor R3 monitors the temperature of the air leaving the drum through the exhaust path. As exhaust-air temperature rises, the thermistor's electrical resistance drops in a predictable curve, and the control board uses this data to regulate drying cycles and prevent overheating. When the board receives a signal that falls outside the expected resistance range, it logs error code 2 and halts or interrupts normal operation.

The fault can originate in the thermistor component itself, or anywhere along its associated wiring circuit. A thermistor that has drifted out of specification, shorted internally, or failed open-circuit will produce an out-of-range reading. Similarly, a damaged cable, corroded connector pin, or a loose plug-and-socket connection between the sensor and the control board can create the same symptom without any actual sensor failure. Moisture ingress at the connector is a common contributing factor in dryers, particularly in condenser or heat-pump models where condensation is present internally.

Diagnosis should follow the same procedure used for Error 1, applied specifically to NTC R3 and its circuit. This involves testing the thermistor's resistance value, inspecting the full cable run for damage or pinching, and checking the integrity of the plug-and-socket connection at both the sensor end and the control board end. Resistance testing should be performed with the dryer unplugged from the power supply. If the wiring and connector check out correctly, the thermistor itself is the likely failed component and will require replacement.