2017 DTC P0140B
I’m getting a P140B code on my 2017 2500HD L5P Duramax, which suggests the EGR valve response is slow. This code is being read on an older model Edge monitor, which was originally used on my old LB7 2001. The trouble code has been confirmed using a GM Tech II scan tool. I have no check engine light at the moment. I can clear it, but it reappears the next time I read the DTCS. Should this be something to be concerned with or just a false alarm? If the check engine isn’t on, I wouldn’t have known about it and am thinking it should be looked at, but it’s not suggesting immediate action. I saw this code earlier in the week, and the check engine lamp did come on. However, after the third restart, the lamp did not return and I’ve put some 450 miles on it since, and still no check engine lamp.
One of our GM dealer’s service techs noted the code in the history, and further diagnosis suggested that there was “too much airflow” at the EGR, hence the code. However, I do recall that we got a bit of snow on the day the SES lamp was set (I probably pushed some into the duct when I was cleaning off the hood). My tech mentioned that the air induction system facilitates an accumulation of snow on the air filter, which should’ve restricted the airflow (odd that “too much” flow was being reported).
I tried getting a replacement air filter to keep in the event another blockage occurs. Sadly, no one carries one—not Auto Zone, Carquest, NAPA nor my Chevy dealership! No dealership in my general area stocks one! You’d think that after a year since introducing the L5P, dealers would have one of these on hand. Also, the owner’s supplement for the Duramax has a GM p/n 84030829 for this filter; however, my dealership states the number should be 84130829—does that suggest a typo in the owner’s manual as well?
I was thinking about a K&N replacement element, but that faces the same risk for getting plugged with snow too if GM doesn’t address this issue. Just a heads up for you L5P owners operating in cold/ snowy climates.
Gary Sanders Milwaukee, WI Whether it's the variable-vane turbocharger or variable-position EGR used by the Duramax 6600, the position sensor can sometimes drift out of calibration. A technician with a Tech II scan tool can test the EGR system and recalibrate the position sensor. The Tech can also exercise the related components through their range of motion to verify correct operation. Otherwise, what you saw might be transitory and may not return. We recommend visiting your local dealership to have it looked at and to establish a document trail. I suspect it's not serious, but please let us know what develops.