The EGR (Exhaust Gas Recirculation) system introduces a controlled amount of exhaust gas into the intake manifold. This helps to reduce emissions by lowering the combustion temperature and reducing the formation of nitrogen oxides (NOx).
If the P0401 code is set, it means that the PCM (Powertrain Control Module) has detected that the EGR flow rate is insufficient. This could be due to a problem with the EGR valve, EGR solenoid, EGR control circuit, or DPFE (Differential Pressure Feedback EGR) sensor.
Common causes of P0401:
* Faulty EGR valve
* Blocked EGR ports
* Faulty EGR solenoid
* Faulty DPFE sensor
* Wiring problems
Symptoms of P0401:
* Illuminated Check Engine Light
* Engine performance problems
* Loss of power
* Increased fuel consumption
How to fix P0401:
The first step is to inspect the EGR valve and EGR ports for any blockages. If there is any build-up, it should be cleaned off. If the EGR valve or solenoid is faulty, it should be replaced. If the DPFE sensor is faulty, it should also be replaced.
Once the problem has been fixed, it should be possible to reset the P0401 code. To do this, you will need a scan tool.
