Northstar Engines and System Technical Discussion Discussion, 2002 SLS Code P 0401 in Cadillac Engine Technical Discussion; Hello all and Happy Holidays! I am trying to help a friend with his 2002 SLS.. He cant pass inspection ...
Hello all and Happy Holidays! I am trying to help a friend with his 2002 SLS.. He cant pass inspection because of the SES light on and a code P401 ( EGR System Insufficient Flow)...He replaced the egr valve with a new Delphi unit and he is still getting this code.. I have read up on this subject a little bit but I am still confused about whether there are egr passage ways in the intake or head that also need to be cleaned out.. And if there are not any, what else could be the problem..Any insight into this problem would be greatly appreciated.. Thank you all for your consideration..
Automobile(s): White Diamond '03 DHS (with DTS floor shift)
Re: 2002 Seville SLS Code P401
The EGR passages on the Northstar are in the crossover manifold and are large enough that they should never need cleaning if I remember correctly. Can't imagine what would cause that code if the EGR was replaced. How long ago was it replaced? Could it be a historical code? If so, it will clear itself after 3 ignition cycles or you can clear it yourself via the DIC.
It was replaced a few months ago but immediately after clearing the codes it came back the same day and has been there since..He is all of a suden paying attention to it because of the upcoming inspection..
If the exhaust manifold feed pipe or the port from the EGR chamber in the crossover casting is/are plugged with carbon, that will set P 0401. You not only have to check the EGR motor assembly itself, upon inspection/replacement you also need to clean out all the ports.