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Juan Crespo
Juan Crespo, Tech Trainer
Category: Car
Satisfied Customers: 1523
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I have an 02 Mitsubishi lancer and ive changed the intake

Customer Question

i have an 02 Mitsubishi lancer and ive changed the intake hoses and the egr valve itself but its still throwing a the p0401 code
Submitted: 10 months ago.
Category: Car
Expert:  Juan Crespo replied 10 months ago.
Hi there.DTC P0401 simply means the computer has not detected EGR flow. Possible causes for this code include faulty EGR valve, hoses, EGR solenoid, wiring, Manifold Differential Pressure Sensor, PCM and obstructed EGR passages in the intake manifold - in this instance we can omit testing the valve and the hoses since you say they have been replaced.The easiest way to test this system is using a scan tool that can read pertinent PID. Not having that scan tool makes the diagnostic process much longer and more labor-intensive.What size engine are you working on?