I have a 98' with 82000 and i just replaced the ERG valve because it ran PO401 on the OBD II and then had the codes cleared and now the check engine light came back on. ERG valve new so what could it be now??

 

most of the time the p0401 code is caused by the DPFE sensor. You can find the sensor by following the rubber hoses that come off the metal egr tube they end at the sensor. with the milage on your truck it would be a good idea to replace the sensor and remove the throttle body and adapter take the egr valve off the adapter and clean the egr passages in the thottle body adapter this will fix it .

 

Next time, before swapping out parts, perform a search on "P0401".

You will find several suggestions on properly diagosing the reason for the fault code and will save yourself a lot of time and trouble.

Steve

 

Just to reiterate what sho said/means just because you get a code doesn't mean a part/sensor is bad.

Something caused the code to be set which in turn gives you a place to start a diagnosis. (not what part/sensor to replace)

As noted above it is very common on these engines for the EGR passages to clog up. It is not common for the EGR valves to go bad.

 

I keep getting the PO402 code on my truck after it clears the truck will go about 30 to 50 miles and it trips the Service Enigine soon light it will be like that for 500 to 600 miles and clear 30 to 50 miles again.