This paper introduces the principle for recognition of engine work -wave signal with neural net-work. A diagnosis method for recognizing engine trouble by its ivork wave is proposed. The designing process is illustrated by diagnosing the voltage trouble of the fuel injector of an electronic control (EC) engine. This paper introduces the principle for recognition of engine work-wave signal with neural net-work. A diagnosis method for recognizing engine trouble by its ivork wave is proposed. The designing process is illustrated by diagnosing the voltage trouble of the fuel injector of an electronic control (EC) engine.