Method for diagnosing an electrically driven compressor

A method for recognition of errors in an electrically driven compressor or booster (12) in a combustion engine has the following steps: a value for output power is determined using a compressor model with the current operating parameters; a value for the power taken by the compressor's electric motor is determined from a further model using electrical supply parameters; and an error recognition unit generates an error signal when the difference between the two power values exceeds a threshold.