Multiple DTCs P0401, P0402, P0403 & P0405

[Benito]

I haven’t had my 2015 long enough to study how the egr system works yet. I am a diesel tech on off road equipment so I’m familiar with how most systems work. The egr valve is usually commanded open based off what sensors are telling the ECM. I assume there’s a temperature and pressure sensor in the intake along with a pressure sensor in the exhaust. If the ECM is not seeing the pressure and temp it wants in the intake it will command the egr valve open further trying to achieve that. Eventually it gets to a point where the egr is open more than the threshold and it sets a DTC. This is usually in the 90% area. Usually the root cause is a plugged egr cooler and dirty sensors in the intake side. If it’s possible with Alfa run a EGR test and watch the valve position. If it makes a full sweep it should be good. I’ve been told not to do a egr valve value reset on a used valve because it will mess up the readings at the sensors if a new value is learned on a valve that may not close or open completely due to soot contamination. Sorry for the long vague post. I just haven’t taken the time to learn this system yet because we don’t use Cummins engines where I work.

Thanks for the info. Not sure what to do at this point but leaning towards replacing the EGR valve mainly because it locked up in the 97% open position for the last 30 minutes of a 90+ minute mixed traffic drive and most of the codes I have received are EGR valve related. Still stumped as to why I go a low and high boost code as well. Not a big fan of just spraying the parts cannon but need to rule something out.

 

[bcbender]

I am getting codes for under and over boost,

FWIW,.. At 7500mi my truck (2020) had multiple underboost codes occur on a trip, I reset them, came back randomly... RAM dealer(s) told me to drive it till it broke.. YEP it did break in MT outside Billings... set a hard code for underboost and EGR... would not tow my 5er anymore...so went back to Billings and 3 days later got it in the dealer and they replaced the EGR valve... been fine ever since.. ( It drove fine with no trailer.. but would not pull with the hard codes )

JM2C

 

[Benito]

Have been driving the truck with a monitor on, (Alpha OBD), to see what everything is doing. Admittedly I am not sure what is in or out of range just looking for things that obviously look odd. EGR cooler performance fluctuated but was consistently in the 90+% range with the lowest reading about 76% so I assume that is OK. The eGR valve was the only thing that seemed off. I noticed minor changes in the percentage open at idle but the engine tone changed significantly - almost sounding like it was put under load. It sounds odd but I was wondering if maybe the valve was functioning but the position sensor , (built in from what I read), went bad so I replaced it. I ended up picking up a remand unit from the dealer. They had 2 in stock and the price was $100 less than the cheapest one I saw in the aftermarket online or my local part stores, ($614). Installed it last night immediately noticed the idle did not change tone like before. Took for a short drive, only 10 miles with MILs popping up- maybe that was really it? I will know for sure in the coming days- have a 1700+ mile round trip coming up next week if not before I will know for sure then.