The P1401 code indicates that the engine computer is detecting an abnormally high voltage in the Differential Pressure Feedback EGR (DPFE) sensor circuit. This usually means the sensor signal wire is shorted to a power source, or the DPFE sensor itself has internally failed. Because of this high input, the computer cannot accurately monitor or control exhaust gas recirculation flow.
The internal electronics of the DPFE sensor commonly fail, causing it to output a constant high voltage signal regardless of actual exhaust pressure.
The signal wire between the DPFE sensor and the engine computer may be chafed or melted, shorting against a power source and causing a high input reading.
Moisture intrusion or corrosion in the sensor's electrical connector can bridge terminals, sending an incorrect high voltage back to the computer.
If the ground wire to the DPFE sensor is broken or disconnected, it can cause the signal voltage to float high, triggering the code.
The engine computer itself is rarely the cause, but an internal failure in the reference voltage circuit could theoretically trigger this high input code.
You can typically drive it for a short time, but the engine may run rough, hesitate, or stall. Prolonged driving with an improperly functioning EGR system can potentially damage the catalytic converter.
No, P1401 specifically points to the DPFE sensor or its electrical circuit, not the mechanical EGR valve itself. The EGR valve might be perfectly fine even when this code is present.
Replacing the PCM is almost always the wrong fix for this code. The DPFE sensor or its wiring is the culprit in the vast majority of cases, and drivers are commonly misled into replacing the computer. Replacing the PCM without thorough electrical diagnostics is an expensive mistake.
The DPFE sensor measures the pressure difference across a restriction in the EGR tube. This tells the engine computer exactly how much exhaust gas is flowing through the EGR system so it can adjust fuel and ignition timing accordingly.