Engine/Transmission (1994 - 1998) P0401 EGR flow insufficient ???

[JesseGray]

The check engine light came on, and produced code P0401, EGR flow insufficient.



I have cleaned a sensor on the intake manifold, I have replaced the vacuum switch, I have cleaned the crude out of the vacuum EGR diaphragm thingy, and it now opens and closes when operated by a hand vacuum pump.



I reckon I now need to clean the EGR cross tube. Would this tube be cleaned sorta like a shotgun?



Are there any other things you think I should check to correct this code?



What effect does this problem have on the overall operation of the engine and performance?



Thank you for assisting an older newby



Jesse...

 

[JesseGray]

P0401 EGR flow insufficient ???

The one thing I have not checked is the the DPFE sensor.



Does anyone have an drawing or picture of what I am looking for?



Thanks,



Jesse...

 

[jtwcummins]

The best thing is to block the EGR. If you take the intake manifold top off there is probably several inches of soot. The code you are getting is caused by the EGR being opened by the ECM and not detecting a 10* rise in intake air temp.

I removed the EGR completely on my 97 when I put on ATS exhaust manifold and Banks Power Pac.



The code can be defeated by using a relay and resistors. The relay replaces the EGR solenoid and resistors are wired to the IAT line at back-top of intake

 

[JesseGray]

P0401 EGR flow insufficient ???

Thanks JTWCummins. The IAT that you discuss, is that pipe plug temp sensor ( P/N 3932272 3536) on the rear half of the intake manifold, aft of the induction tube from the charge air cooler??