Alex Bruene Posted May 20, 2016 Share Posted May 20, 2016 Good afternoon gentlemen... I'd like a little input on an impossible to diagnose P0401 on a 2015. Here's the story... About 20,000 km ago, I replaced the EGR cooler for a restriction, which rectified the issue for the time being. Now, a month later (yes, they drove 20K in a month), I am getting the same DTC again. I ran PPTs W, AZ and J, and every thing comes out clean. I removed and disassembled the cooler, and it is perfectly clean. I replaced the EGR valve on a hotline suggestion, as apparently early build 2015's had EGR valve issues. That kept the light out for 100km, and it came back on. Again, I ran all the diagnosis, and it's clean as a freshly bathed baby. FWIW, this truck has just under 300,000km. 12,000 engine hours and 8,000 idle hours. Do you guys have any suggestion or experience with such an issue? Quote Link to comment Share on other sites More sharing options...
8WA Sman Posted May 21, 2016 Share Posted May 21, 2016 Any clues in the FF or Mode6 data. Sorry I don't have any real world tips. Quote Link to comment Share on other sites More sharing options...
sneakypete Posted May 22, 2016 Share Posted May 22, 2016 Wondering if you have a skewed maf sensor Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted May 23, 2016 Author Share Posted May 23, 2016 I was thinking that, but I have also gone over PPT J a few times... and, sent my results to the good folks at hotline to review. They also agree everything is working properly. I'm going to remove the MAP on Tuesday to clean it, as well as swap a MAF from another one of the same fleets' trucks and try it out. Quote Link to comment Share on other sites More sharing options...
lmorris Posted May 24, 2016 Share Posted May 24, 2016 Have you checked the lower intake? There have been a couple of posts in other threads about build up causing EGR codes and NOX codes. Have a fleet customer that has had to clean out a few of their's that have been doing this. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted May 24, 2016 Author Share Posted May 24, 2016 I have not. I will do so. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted May 24, 2016 Author Share Posted May 24, 2016 Yeah... The lower and upper are pretty gross and gunked up. I have them soaking right now. I'll put it together later today, or in the morning and see how it goes. Quote Link to comment Share on other sites More sharing options...
mchan68 Posted May 24, 2016 Share Posted May 24, 2016 I had one with a stubborn P207F that wouldn't go away until I replaced the SCR. It came back shortly after, with a P0401 that I needed to replace the coolers on, after already having replaced it 25000 kms earlier. The intake on this particular one was very caked up with carbon. After bead blasting the intake and going back together, I haven't seen him back since. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted May 25, 2016 Author Share Posted May 25, 2016 I took this one out, soaked and pressure washed it. I couldn't believe how bad it was. So far, it's working fine... Quote Link to comment Share on other sites More sharing options...
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