So I really hate this P0401 code, just popped up on me again after I just replaced the DPFE sensor and time is running short until my emissions have to be done. I picked up a EGR valve mounting gasket today so next step will be to clean out the EGR valve as much as I can. I need help, any ideas of wat else could have caused this code to pop up?

 

Come on guys, I know somebody has gotta have some sort of idea about this, any and all help would be appreciated, but I gotta get this figured out.

 

I'm not clear on your P0401 code repair.

I know you said you have a beat on 98 4banger & from your DPFE thread that you did some research on your P0401 code & ordered the less expensive DPFE sensor from RockAuto.

Did replacing the DPFE sensor fix the problem for a while, but it returned????

Or did you just replace the DPFE on a researched hunch, without doing any EGR system testing, erased the code & hoped for results????

You could have more than one problem, so you need to visit the Tech Info thread as as been suggested & do some EGR system component trouble shooting, to determine which component/s are acting out & replace the faulty one/s.

You could have a vacuum leak to the system, a bad vacuum switching valve diaphragm, that controls vacuum switching to the EGR valve, dryrotted/leaking vacuum lines to either, if the engine is burning oil, or has had the wrong srevice grade oil used, or a clogged up PCV valve thats caused oil comsumpton, the system may be clogged up with carbon & needs cleaning, or maybe the new aftrmarket DPFE sensor is acting out.

Unless the EGR valve is rusted up & falling apart, they rarely go bad.

The P0401 suspect list usually goes about like this, DPFE sensor, leaking/dryrotted rubber vacuum lines, faulty/leaking vacuum switching valve diaphragm, carboned up system, faulty/leaking EGR valve diaphragm, bad/rusted out EGR valve, faulty EGR valve.

Anyway do the Tech Info thread EGR system tests & component testing/trouble shooting & let us know how it goes.