Circuit Description

The DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit diagnostic monitors the electrical circuitry of the EGR valve. The EGR system controls the formation of Oxides Of Nitrogen (NOx) emissions by recirculating the exhaust gases into the combustion chamber. The EGR valve is a stepper motor design. The stepper motor moves a spring loaded plunger that controls the flow of exhaust gases into the intake manifold. The plunger movement is controlled by the Powertrain Control Module (PCM). By turning the stepper motor in different directions, the PCM controls the opening of the exhaust gas passage to the intake manifold. The stepper motor has 4 coil windings that control the motor movement. The DTC P0403 diagnostic monitors the electrical circuits of the 4 coils.