What is the ford ranger fault code u0401?

The fault code 0401 in a Ford Ranger indicates the EGR flow is insufficient. There are several things that could cause this fault. The main culprit usually is a faulty DPFE sensor. The delta pressure feedback (DPFE) sensor goes bad inside and it won't accurately measure the correct amount of exhaust flow. The second most likely cause are clogged EGR ports inside the intake. The EGR valve allows exhaust gas to flow into the intake manifold to dilute the air fuel mixture. The third most common cause of a 0401 fault is either a clogged exhaust gas orifice or a hole in one of the tubes. There are other issues that could cause the fault to display and may take a professional to properly diagnose the issue.