Error Code P0401: What It Means & What To Do?

<<See All OBD Codes

This trouble code is generic, which would mean that it can apply to all the vehicles which are equipped with the OBD-II or the vehicles which are made since 1996 up to the present. The specifications on the definition, the troubleshooting steps as well as repairs can always vary from one vehicle make to another. This can happen because of a lot of reasons and the mechanic should diagnose the specific cause for this code.

The error code 401 can be defined as Insufficient Exhaust Gas Recirculation (EGR) Flow.

The "insufficient EGR flow" would mean that there are not much exhaust gasses flowing back into the incoming air to the engine. Willing to know what EGR stands for? Full form of EGR is "exhaust gas recirculation".

There are there parts of the EGR system: EGR valve, DPFE (differential pressure sensor EGR) and actuator solenoid.

What causes this problem with the Insufficient Exhaust Gas Recirculation (EGR) Flow?

• Issues with the EGR vacuum switching valve
• The catalytic converter might be clogged
• Flaws in the EGR temperature sensor
• The EGR valve control circuit might have some electrical issues
• Some problems related to engine computer
• EGR passages might be clogged or restricted
• There can be some problems with the DPFE sensor
• The hoses to the DPFE sensor might be defective
• Defaults in the EGR valve
•  EGR valve might be stuck closed
• There can be some vacuum supply issues at the vacuum-operated EGR valve

1. MAP Sensor - Do you remember when was the last time you got your car MAP Sensor checked up? A defective MAP Sensor can cause a lot of issues like displaying P0401 code.
2. Catalytic Converter - Poor Catalytic Converter can cause a lot of difficulties, so why not get it replaced at time?
3. EGR Valve Gasket - Are there some faults in your EGR Valve Gasket? Don’t waste time and get them replaced or else P0401 code can turn up.
4. Engine Coolant Temperature Sensor - OBD Code P0401 can appear because of faulty Engine Coolant Temperature Sensor.
5. Crankshaft Position Sensor - Everything is fine with Engine Coolant Temperature Sensor and still P0401 code triggering? Then you must get your Crankshaft Position Sensor checked.
6. Mass Air Flow Sensor - There can be some issues with the Mass Air Flow Sensor due to which you may see P0401 code appearing over and over again. Visit us to buy best quality Mass Air Flow Sensor online.
7. Oil Pressure Sender - A lot of issues can arise do to defective Oil Pressure Sender. Did you just see P0401 code flashing? Now you know the reason why it is appearing. Get it inspected and replaced on time.

Our main motive is to achieve customer satisfaction and that’s why we will help you to diagnose P0401 code by mentioning some major symptoms below:

Common Symptoms

• The engine might fail emissions from excessive NOx in the exhaust tests
• The check engine light can start illuminating and the code might be set in ECM memory
• The engine might have an engine ignition ping or knock on acceleration

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P0401:

• The leaking or clogged EGR valve should be replaced
• If you find out that there is a broken vacuum line to the EGR valve or control solenoid, then it should be repaired or replaced as per the need
• Make sure to replace the EGR temperature sensor or clean the carbon off of it to repair it if it does not register enough of a temperature change
• Carefully clean the carbon out of EGR tubes to intake manifold to clear any blockages

There is no need to get strained if your OBD Code is still flashing up as we are here at your service. Have a look at our superior variety of Egr valve, Throttle Position Sensor, Mass Air Flow Sensor Cleaner, Egr Temperature Sensor and many more. Now all your problems would vanish within no time.

Here are some steps which you should follow in order to diagnose this fault code:

• First of all you should carefully scan the codes and document the freeze frame data in order to verify the problem
• All the engine and ETC codes should be cleared and road test the car to verify whether the code comes back
• Visually check the vacuum hoses, wiring, and connections to the EGR valve and control solenoid along with the EGR temperature sensor
• Then disconnect and check the EGR valve is getting vacuum to the valve when the control solenoid opens on light to medium acceleration
• The EGR temperature sensor change should be checked and engine to bog down when the EGR is opened
• Remove EGR valve and temperature sensor to check for excessive carbon build-up or blockage of EGR tubes

Common Mistakes When Diagnosing The P0401 Code

• A common mistake can be failing to check and clean the EGR passages when replacing a faulty EGR valve
• Condemning a good EGR valve when the EGR temperature sensor has excessive carbon build-up on it causing the failure code
• Mistake of failing to check to see if the EGR control solenoid will hold vacuum before replacing the EGR valve

P0400 - Exhaust Gas Recirculation Flow Malfunction

P0402 - Exhaust Gas Recirculation Flow Excessive Detected