Bosch Dryer Error Code 1

Error code 1 on a Bosch dryer signals a fault with the NTC R4 thermistor, the temperature sensor located in the air current in front of the heater. The dryer uses this sensor to monitor incoming air temperature, and when the reading falls outside the expected range, the control module shuts down and flashes the 'Drying' LED to alert you. The fault can be caused by a failed sensor, a wiring problem, a bad connector, or an installation environment that is below 0°C.

No, you should not continue operating the dryer while this error is active. The NTC R4 sensor provides the control module with temperature data used to manage the heater safely, and running the appliance without a reliable reading from that sensor creates a risk of overheating. The dryer's built-in protection has already halted operation for this reason, and normal use should not resume until the fault is diagnosed and corrected.

If the fix is simply reseating a loose connector or moving the appliance out of a freezing environment, there may be little to no cost involved. Replacing the NTC R4 thermistor is a relatively affordable repair, with parts and labor typically ranging from around $75 to $200 depending on your location and service provider. If the wiring harness also needs replacement, costs can rise toward the higher end of that range or beyond.

If the dryer is installed somewhere that gets below 0°C, the fix is simply moving it to a warmer location or waiting until temperatures rise. Beyond that, resolving this code requires disconnecting the sensor cable from the power module and testing the thermistor, cable, and connectors with a multimeter, which is a task suited to someone comfortable with basic electrical testing. If the thermistor or harness is confirmed faulty, replacing those components will require some disassembly of the dryer cabinet.

A power reset may temporarily clear the displayed fault, but the underlying problem with the NTC R4 thermistor, its wiring, or its connector will remain. If the sensor continues to produce an out-of-range signal, the error code will return as soon as the dryer attempts to run a cycle. Proper diagnosis and repair of the faulty component is required for a lasting fix.