i have 02 yukon denali with radix intercooler supercharger, couple of months ago i had the service engine light come on and I took it to the dealership to run an scan on it and it read PO401 problem with the egr value, not seeing enough exhaust, so the dealership replace the egr value with a new value-- couple of days later, the service engine light comes on again and the same code show up PO401, i call lydon at wester tune and told him the problem and he sent me a new pcm without the egr setting, install the new pcm and service light engine did not come on but after i turn off the engine and turn it on again the service enigne light comes on again but the code is PO405 call wester tune again and lydon told me that he need the pcm again, he told me that he will shut the egr assembly completely off.

i have jba headers on it and my friend shop check the header at the egr value to see if it is clean and sure enough it is clean--- has anyone have this problem before, i just don't want the same problem to occur again.

 

Why would you tune around a mechanical problem? Tuning it out is not going to fix it.

A code P0401 most likely means one or more of the following has happened:

* There is a blockage in the EGR (most likely carbon buildup)
* The EGR valve is faulty
* The EGR valve may not be opening due to a lack of vaccuum

In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.

* Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's. There should be a noticable difference in RPM's with the EGR open
* Clean out the EGR valve to remove deposits
* Replace the EGR valve




Stop sending your PCM in and check out your EGR system for issues.

 

i had the egr value replace and clean to replace the desposits, the dealerships reply it as to do with the computer not reading correctly, physically according to them it is fine, so i call lydon at wester garage to fix the problem and it just disable the egr system, but know i am getting a po405 code due to him disablely the egar system.

 

if it has worked all this time, and set a code now its not the computer.