I have a 2013 Ram 2500 with the Cummins. My problems started when the turbo actuator failed. After replacing and properly calibrating the actuator, I discovered several sensors had gone bad, the MAP sensor right after the throttle valve, the exhaust pressure sensor, and the MAF sensor. I also cleaned the EGR valve and cooler. At this point the truck has a ton of power, however, I'm getting a recurring P0401 code and at times I'll start it up and it just feels gutless. I know, as I just had it apart, that the EGR cooler and valve are clean, not blocked and moving freely. I can't think of much else to look into, as I've replaced everything I knew or could find was bad, but this code is throwing me, since I have already serviced the EGR. My only two ideas are a bad EGR temp sensor, or possibly the exhaust pressure sensor. While the pressure sensor is new, it was the only one that wasn't genuine Cummins, as my dad actually bought that one. Given that I'm now down to a single DTC that doesn't complain about a specific sensor (IE exhaust pressure sensor out of range, replacing it resolved this, and I swapped the old one back in and got the code again, just to confirm I wasn't blindly throwing parts in it...) I'm a bit hesitant to just buy the temperature sensor and change it. I'm also unsure of the possibility that something else could be wrong, but I literally can find nothing about P0401 that mentions anything other than dirty EGR devices.

I'm at my wits end with this nonsense, and since I'm finishing a nice big job this weekend, and getting paid... Despite really not wanting to actually pay someone to deal with this problem, if I can't solve this myself this weekend, its going to the stealerership next week. Short of any better ideas I'm also strongly considering rolling the dice on just changing that EGR temp sensor just to see if that does anything, although I realize that would be just throwing parts at the wall to see what sticks.

 

Apparently, it might be as simple as low vacuum signal to the EGR valve, so it doesn't open as far as the ECM would like. Also might be a bad sensor, or sensor wiring.

 

I've thought about the EGR actuator, but, being that its a stepper motor driven one and not vacuum, I'd imagine I'd get some kind of code about the position not matching what was called for? If its not getting the right signal, then I'd assume a ECM issue? There's no vacuum system of any kind on this truck.

I'm really hoping its a sensor and not wiring, but I'm just not sure how to test this either way. It really seems like I'm getting too much EGR and the ECM is reading too low, which would likely be a sensor, or potentially a wire problem.Yesterday, I removed the sensor I'm probably just going to replace, and it was covered in soot, not too surprisingly... I wiped it off, and the probe is definitely darkened and had what looked like some pitting towards the end on the side I believe the EGR stream hits. After doing this, the truck hasn't given me a check engine light, or gone into a de-rated state, but the power is just underwhelming until 2500 RPM. Before messing with it, I was either de-rated or getting boost immediately on pressing the pedal, which is how I believe it's supposed to be. Right now it feels more like an old fixed turbo than the VGT. Since this EGR temp sensor is only $60 something from Cummins, I'm going to get one on Monday just to see. A good friend suggested I try and locate a scan tool that can read more data streams/codes than the standard cheap-**** one I have, so I can read things like EGR position and the various sensor values, assuming I can find a reference as to what they're all supposed to look like. If none of this pans out, its going to the dealer or some sort of shop.

 

Let us know how it turns out.

 

Sensor went in tonight, and all was well on the ride home. I gave it a couple opportunities to nis behave and it did not. Until its been driven around for a few days I wont consider it fixed. The last 1/3 of the sensor towards the tip was pitted on the side that faced the oncoming stream. Overall I’d describe it as looking like a cooked thermocouple. This and the fact that it is the sensor it relies on most for controlling EGR flow, I’m feeling optimistic. Will report back with the good, bad or ugly…

Naturally, now my blower fan is acting up, and giving me awful flashbacks of the trauma I endured with my Durango… more on this in an appropriate thread.

 

Nope, not fixed…

Really quite disparaging that no one has a clue!

And I’ve just noticed it’s absolutely peeing through DEF fluid, not as in leaking it out, actually consuming it at a high rate. Seems we may have to investigate all the parts everyone has been to busy taking off to figure out how to fix…

 

Have a read thru this, see if it is any help.