Q: Engine light on

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My Engine light is on due to an error code P0401.

Hi there. A code P0401 indicates that the EGR system is not working properly. The EGR, or exhaust gas recirculation system, is used for emissions to reduce the NOX emissions. If it’s not functioning and opening as it should, then this code will come up. Most of the time, the failure is due to a bad EGR valve or a failing EGR solenoid. I would typically use a computer scan tool to cycle the solenoid and see if it comes on. I could then see if the EGR valve is functioning by applying vacuum to it while the engine is running. This is best diagnosed with a computer scan tool. I would suggest getting some assistance from a certified mechanic from YourMechanic to make the repairs.

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