yeah, i finally solved the problem with the P0401 CODE on my 97 bonneville 3800 vin K

believe it or not, it was caused by the repair shop leaving the PCV valve out when they changed the upper plenum...

it sits directly below the MAP sensor... they swapped the plenum and left the PCV valve in the old part... it caused the code to set...

i found out, that code is more about the MAP SENSOR'* ability to sense pressure change in the intake manifold when the egr valve is commanded on by the computer, than whether egr gasses are flowing or not...

since the pcv valve was missing, the MAP SENSOR was sensing no change in the intake manifold pressure, which told it the egr wasn't flowing... but it was really the fact that the PCV VALVE wasnt allowing the manifold pressure to build to a point that it could drop when the egr opened.... this in turn sent a false signal to the MAP SENSOR...

all over a missing PCV VALVE...
now a faulty one, (sticking open) could cause the same problem....

hope this helps you...

check or replace the PCV VALVE cheap insurance for less than $5 bucks..

camljr@juno.com

Good Job!!!!

Cam, repeatedly posting exactly the same text in several topics clutters the database. It also can be confusing for members that don't have the same problem as you. A missing PCV valve is extremely rare. Please stop posting the same text over and over, and please stop digging up topics from 2003.