P0401 never ending code

[wml52]

Several months ago my MIL lamp posted a P0401 code “EGR Insufficient Air Flow” The following parts were tested and replaced where necessary: VSV for ERG, EGR Vacuum Modulator, Vacuum Hoses, Thermostat. The passageways for the EGR valve were also checked for carbon buildup but it was clear. The EGR valve was OK via vacuum test.

The MIL Lamp was reset, however after driving approximately 30 miles the MIL lamp tripped another P0401 code. A certified technician checked the system again but to date no reason could be found to trip the code. He is at a loss as to what might be causing the code.


Each time I reset the MIL I travel approximately 20-30 miles before the code trips again.


At this point I would appreciate any suggestions as to what else I might check?

Thank you,

Bill

[good_old_geo]

i think your intake manifold needs cleaning. that just happened to me there is a DIY intake manifold cleaning thread on the forums. Its pretty easy.

remove the intake hose

remove the throttle body (4 12 mm bolts). Save the metal gaket.

there are 2 allen wrench and 2 12 mm bolts that hold the upper half of the intake manifold to the lower intake manifold. Take these off and save the metal gasket.

start cleaning. I would just scrape off the gunk first. a shop vac would be helpful. Mine had 225 k miles when I did this. Some throttle body cleaning spray would also help. Clean out the passages that connect to the egr valve.

Once clean put things back together.

I was getting 26 to 28 mpg before the cleaning and now my car is back to 36 mpg

[wml52]

Thanks for the post, I'll give it a try. Lord knows I've tried just about everything else except replacing the computer and I doubt very much it's that.

Bill