6.7 Cummins P0111

Feb 25, 2015
Sask, Canada
So a bit of a back story. 2017 ram 3500, ISB6.7, 106,000km. Its been deleted since 100k. So please bare with me.

A couple weeks back it threw P0111, which indicates issues with the IAT sensor which is mounted on the air box.

Pulled the sensor, it looked just fine, clean and provided resistance that varied with airflow over the element. The harness was providing 5 volts as well. The code would clear but come back right away. I was getting some odd temp readouts while driving, they would most of the time mirror ambient. I would get it to jump 20 or 30c on deceleration some times. The code cleared itself once for a short period but then returned.

I also noticed a drop in fuel economy. Had got a high of 17.7mpg on winter blend some time before but now could only muster 16 on summer blend. I was also hearing increased clatter under load, some weird turbo surging and the odd miss and an increase in smoke on start up and acceleration.

I installed a new, non OEM sensor and was able to clear the P0111 but then was getting P2580, which indicates turbo speed sensor issue. Well I doubt that since it correlated to switching the new sensor.

Further reading recently and tying into stuff I read years ago showed that the IAT, MAP and turbo speed sensor are tied in together and may throw weird codes, not necessarily a correct one.

Today I got time to do some more trouble shooting. Pulled the MAP and as I suspected, it was coated in egr trash. It provided resistance and was easily cleaned with the proper sensor cleaning spray. Put it back in but got a pile of temp range, MAP range and service throttle codes. Great. Oh wait, sometimes, well mostly you need to plug the sensor back in. After some cycles I could clear the codes but was still getting P2580. I popped in the old sensor and was able to clear all codes. The exhaust note changed, no smoke and after a short drive, engine on/off cycles and some pss revving, no codes. I will obviously monitor but am now hopeful she is back on track.


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Are you saying you forgot to plug the sensor back in and that's why you got the codes after cleaning the sensor?
In the scanner live data you out to see what the readings are and compared to a known good value.

I monitor my MAF readings and have notice when it needs cleaning or replacement.
Yes, to clarify, I was only getting the P0111 and P2580 prio but got the whole pile of different codes when forgetting to plug the MAP back in. I had a holy cow moment before realizing my mistake.

I will see what the BD tuner displays for data. I think having a MAP readout now would be very beneficial.
So I got a few hundred km today towing in the heat. All was well until 3/4 the way home. The truck chimed and I saw the IAT climb from 25c to 77c and then slowly drop back down.

I was not able to clear the code and noticed that the inlet temp climbs when I decelerate with the exhaust brake but no temp change with the EB off.

Got home and cleaned all sensors, which were unchanged from last time. No effect on the P0111. I swapped in the different IAT sensor and while the P2580 did not return, the P0111 remained, along with the weird VGT noises.

My next step is sourcing a new OEM MAP sensor and checking from there. My MAP, while clean looks somewhat used up. The coating on the element is wrinkled and not consistent with every other similar sensor I have dealt with.
I had exactly the same model truck, I had a very interesting conversation with a cummins engineer who warned me off deleting my truck.
He said the Engine would not benefit ,neither would fuel consumption and the ECU/ECM would not respond well to an aftermarket tune.
Great Engine.
Well I partially agree Contractor K. Since deleting there has been some nuances that surfaced. Well perhaps nuances are not the proper term. There has been some jerkiness when disengaging cruise, somewhat harsher shifting with the AS69RC from 3 to 4 when towing heavy and on the go pedal. But on the flip side, I have seen some solid, hand calculated mileage gains.

I certainly wish I never had to delete but unfortunately FCA backed me in a corner. 80,000km warranty on critical parts that are prohibitively expensive and learning later most were on back order. DEF systems may work well for pavement queens on the clean asphalt of the southern US, they are notorious for failures up here. No brand escapes the issues up here. Thats reality.

While it's possible P0111 could be some tuning anomaly, I have considered removing and reloading the tune, what can it hurt?
Is the EGR valve still active? I don’t know how this cummins is set up from factory but it may be that now you’ve deleted the DPF you are now getting more soot into the intake via EGR than before. A lot or EGR systems now take the gas from after the DPF so it’s clean (no soot). Withought the DPF you can remove the EGR valve just take out any throttle butterfly in the intake aswell. Whoever it was that did your ECU map should be able to set these to closed and open respectively. This may not help with your current fault but will stop further soot build up in the intake system.
The EGR should be turned off. I say should and beleive it to be. From what I gather, BD gives no options, it shuts all emissions devices off and turns the throttle butterfly off. I could confirm by removing the egr crossover tube.

I had driven a few hundred km prior and rechecked my MAP, which was was still spotless from the last clean. I surmise of egr was on or leaking, there should be some residue.
So a bit of an update;
This pertains to my ongoing P0111. It randomly comes on only in the warmer months, we just lived with it as its winter here 15 months out of the year.

My wife said fix the **** thing before any other projects. Plus she sold the 5 horse and got a 6 so she plans on putting miles on.

I went back to examine the problem and what i found along the way. Issue was that I was asking the wrong questions. My monitor was giving me IAT readout, which I wrongly assumed was inlet temp at the air box. Sensor cleaned/changed with no luck. MAP cleaned/changed, again with no luck.

Issue I saw was IAT changed with boost or exhaust brake use, thats not right, dug further and learned the IAT readout is of another sensor, the intake temp sensor, which is burried on the intake shelf near number 5.

Minimal things found about it online but do know this. Cummins 2872858 which is also used for the EGR crossover tube temp sensor. You have to really contort your spindly arms to get at it. Loosen the Aisin trans dipstick tube to gain a bit more. Found the best way was as I lay on the engine bay, string my right arm under the master cylinder. Looks to be a 25mm hex deep socket, which I didnt have. Its not a heavy torque (practiced removal on the EGR sensor). Used small vice grips.

So what i found was twofold; the main routed wiring harness sits right on the connector, almost wearing through the wires insulation (hard to see in the picture) and the large amount of pre-delete carbon coating it.

The senosr itself looked just as dirty as the EGR sensor but easy to clean with sensor clean. I used liquid electrical tape to seal up the wires and used a zip tie to keep the main wiring harness off of it.

Initial test drive was good, CEL never came on or any others for that matter. I'll keep you guys in the loop on it. Hopeful its the solution and might be able to help someone else.


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