P0402 Buick Exhaust Gas Recirculation Flow Excessive Detected

P0403 Buick Exhaust Gas Recirculation Control Circuit

Possible causes
– Faulty EGR volume control solenoid valve
– EGR volume control solenoid valve harness is open or shorted
– EGR volume control solenoid valve circuit poor electrical connection
– EGR temperature sensor and circuit
What about the obd code?
An improper voltage signal is sent to ECM through the valve
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Possible engine hesitation
P0403 Buick Description

Early Exhaust Gas Recirculation (EGR) systems component s include and EGR Valve, and Engine Control