Engine Light ON (or Service Engine Soon Warning Light),Possible engine hesitation
P0400 Possible Causes
Exhaust Gas Recirculation (EGR) volume control valve stuck closed,Faulty Exhaust Gas Recirculation (EGR) volume control solenoid valve,Faulty EGR Valve,Faulty EGR temperature sensor and circuit,Exhaust Gas Recirculation (EGR) solenoid valve harness is open or shorted,Exhaust Gas Recirculation (EGR) solenoid valve circuit poor electrical connection,Dead (Weak) battery
P0400 Description
Early Exhaust Gas Recirculation (EGR) systems component s include and EGR Valve, and Engine Control ??dule (EC?? Controlled Vacuum Switch Valve or EGR Solenoid and an EGR Vacuum ??dulator. Depending on the engine and driving conditions, the EC??will control the EGR Solenoid which will operate the EGR Vacuum ??dulator to regulate the opening and closing of the EGR Valve. The EGR system on recently built vehicles uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the EC?? Two windings are turned ON and OFF in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the EC??does not issue the pulse signal. ??certain voltage signal is issued so that the valve remains at that particular opening.
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