P1401 - FAULT CODE - OBD2

P1401 FORD, LINCOLN, MAZDA, MERCURY: DPFE CIRCUIT HIGH INPUT

Diagnostic code P1401 OBD2 is a manufacturer specific code. It is also defined as "high voltage of the detected differential pressure feedback EGR sensor circuit".  This code is set when the PCM (Powertrain Control Module) finds excessively high voltage in the circuit that controls the operation of the DPFE (Differential Pressure Feedback Sensor), which is a critical part of the EGR System.

The Exhaust Gas Recirculation (EGR) System mixes a certain amount of the exhaust gas in the intake air. In this way, The EGR reduces the combustion temperatures below the point where Nitrogen Oxide (NOx) is formed. In most vehicles, the opening of the EGR valve is electronically controlled to get this result. The Ford manufacturer uses a hole in the EGR duct, which works as a pressure regulator.

When the EGR system and the different components of the system are working properly, the PCM sees the pressure difference that is proportional to the amount of gas that passes through the system hole. When there are variations in the engine speed and load, the PCM uses the signal voltage to calculate the gas recirculation strategy. So, it reduces emissions output without losing engine performance and fuel economy. In case the PCM detected a signal voltage above the right level, the error code P1401 OBDII would be set.

• The Check Engine lamp is on.
• The engine does not run at idle.
• Limited acceleration.
• High levels of engine power loss.
• Increased fuel consumption.
• The vehicle does not pass the emissions tests.

Reasons for setting the fault code P1401 OBD2:

• The Differential Pressure Feedback Sensor may be defective. This is the most common cause.
• The electrical circuit of the DPFE may have bad wires or connectors.
• The EGR valve may be in bad condition.
• Possibly a vacuum line has deficiencies.
• Exhaust gas recirculation system lines or the exhaust may be clogged.