The exact repair would depend on the root of the problem, and there are multiple reasons why code P0401 might be stored. There’s more than one way of fixing any issues with your car, especially if you’re dealing with OBD-II codes. If you’re not confident with the technical knowledge you have, seek a certified mechanic’s help instead of fixing the problem yourself.īut if you would like to diagnose the problem yourself, check out the videos below to get an idea of how to troubleshoot a P0401 code: Obviously, there is more than one potential reason that a code P0401 might be set, and diagnosing the root cause can be a little tricky for the untrained eye.

Engine knocking or pinging during acceleration.

Illuminated malfunction indicator lamp (Check Engine Light).

You may begin experiencing these symptoms if your computer’s giving you a P0401 code: What are the Common Symptoms Of The P0401 Code?

Issues with the PCM, such as software in need of an updateĬircuit problems, such as damaged wiring and loose connections are one of the causes of P0401 code.

Circuit problems, such as damaged wiring and loose connections.

Inadequate vacuum supply to the EGR valve.

A failed sensor (e.g., differential pressure sensor, manifold absolute pressure sensor, etc.).

Trouble codes on cars with pre-OBD-II systems may vary depending on the make and model year. What are the Possible Causes of the P0401 Code?Ĭode P0401 is experienced by all car types that have on-board diagnostics. To learn more about how the EGR system works and how it developed as an emission control technology, check out our in-depth look. This helps lower your engine’s combustion temperature for a reduction in oxides of nitrogen (NOx) emissions. The EGR system is important because it reduces emissions by allowing burnt exhaust gas to flow back into the engine.

Usually on an OBD2 system that sets the P0401, the ECM/PCM must see the failure on two consecutive trips before it will permanently set the code and trigger the Check Engine Light. If by looking at the feedback loop (whatever it may be on the system in question), if the ECM/PCM determines there is insufficient EGR flow, it will set the OBD-II code P0401. What Does the P0401 Code Mean?ĭiagnostic trouble code (DTC) P0401 stands for “Exhaust Gas Recirculation (EGR) Flow Insufficient Detected.” This code means that the computer detects insufficient exhaust gas recirculation (EGR) flow in the system. Code P0401 means that the computer detects insufficient exhaust gas recirculation (EGR) flow in the system.

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