it is your EGR Valve.
EGR stands for Exhaust Gas
Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve
, an actuator solenoid, and a differential pressure
sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine
temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.
A code P0401 most likely means one or more of the following has happened:
- The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
- There is a blockage in the EGR (tube), most likely carbon buildup
- The EGR valve is faulty
- The EGR valve may not be opening due to a lack of vaccuum
In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
- Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
- Clean out the EGR valve and/or tubing to remove deposits
- Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
- Replace the DPFE sensor (with a good quality / OEM one)
- Replace the EGR valve
drivers side of the engine
bay, just under the intake manifold
plenum where the throttle body bolts up! If you take the air snokel off you'll see it better! It has a remote mountted vaccum solenoid with a 2 wire connector
going to it that you should be able to see near the throttle body.
Follow the hose from the solenoid down to the valve and you'll find it!
hopes this helps-------lebones