Bosch Washer Error Code 20

Error code 20 on a Bosch washer means the appliance detected that the heating element was active during a period of the wash cycle when no heating should be taking place. This is described as unexpected heating and points to a stuck heater relay, a faulty NTC temperature sensor, or a problem with the heater itself. The power module, which controls the heater relay, is a common source of this fault. Diagnosis involves checking the NTC sensor, testing the heater, and potentially replacing the power module.

You should not continue running the washer while this error is active. A stuck heater relay means the heating element may be running without control, which can overheat the water, damage fabrics, and place unnecessary stress on electrical components. Stop using the appliance until the fault has been properly diagnosed and repaired.

Turning the machine off and back on can clear a transient version of error code 20 if the fault was caused by a temporary control issue rather than a hardware failure. However, if a component such as the heater relay, NTC sensor, or heating element has physically failed, the error will return as soon as the machine runs through the affected part of the cycle. A reset is always the right first step, but a recurring error 20 requires hands-on diagnosis.

The first step any technician recommends is resetting the washer by turning it off and then back on to see if the error clears on its own. If it returns, diagnosing the NTC sensor and heating element requires a multimeter and basic electrical knowledge, which is within reach for experienced DIYers. However, replacing the power module involves working with mains voltage components and is best handled by a qualified appliance technician if you are not comfortable with electrical repairs.

Repair costs depend on which component has failed. Replacing an NTC temperature sensor is generally a lower-cost repair, typically in the range of $50 to $150 including parts and labor. If the power module needs to be replaced, costs typically range from $150 to $350 or more depending on the specific model and local labor rates. Getting a diagnostic estimate from a technician before committing to any repair is advisable.