Possible causes
– EGR passage clogged
– Faulty EGR Vacuum Modulator Valve
– Faulty EGR Valve
– Faulty EGR solenoid valve
– EGR solenoid valve harness is open or shorted
– EGR solenoid valve circuit poor electrical connection
– Dead (Weak) battery
– Faulty EGR temperature sensor and circuit
– Exhaust gas leaks
– Faulty EGR Vacuum Modulator Valve
– Faulty EGR Valve
– Faulty EGR solenoid valve
– EGR solenoid valve harness is open or shorted
– EGR solenoid valve circuit poor electrical connection
– Dead (Weak) battery
– Faulty EGR temperature sensor and circuit
– Exhaust gas leaks
Tech description
EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts try cleaning the EGR valve, tube and passages.
When is the obd code mean?
– Low EGR flow control is detected
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Possible engine hesitation
– Possible engine hesitation
P0401 MAZDA OBD Code Description