How To: Test whether error code P0401 on a 2004 Ford Focus is accurate

How to Test whether error code P0401 on a 2004 Ford Focus is accurate

Error code P0401 on a 2004 Ford Focus indicates EGR Insufficient Flow, which usually means your DPFE sensor needs to be replaced. If you're not sure though, and you shouldn't be, watch this video to learn how to perform a test that will make sure your DPFE sensor is actually broken before you replace it.