Fault 125 intake manifold 1 pressure
08-12-2022, (Subject: Fault 125 intake manifold 1 pressure ) 
Post: #1
Fault 125 intake manifold 1 pressure
I got this fault code a couple of weeks ago and I have since fixed it. However, the problem was not what I originally thought. I am posting it here to possibly help others. (Rawze, this site is worth its weight in gold.)

I am running a 2017 isx 15 2350 with 20k hours and 900k miles

This fault first presented itself as an engine 25% derate, with NO check engine light. Just the message on the dash. After about 2 hours the message went away. When I got back to the yard I plugged into the engine and the nay fault was the 125 intake manifold pressure message. So I started looking for the leak in the rubbers, none. Next I pressured up the car, held with no loss. Cleared the code and waited for it to happen again. Next trip out, there it was again, 2 hours later the message cleared, but when it cleared it did trigger a check engine light that lasted about 3 hours then gone.

This gremlin kept showing itself like this for 3 weeks while I kept looking for air leaks. I did change the imap sensor in that three weeks but no love. Finally I noticed the pattern. When I was at sea level, and climbed up over 3000 feet, I would get the derate light 30 minutes after cresting. I called my Cummins part guy and asked if these engines had a barometric sensor somewhere. They do, it’s right in front of the imap sensor just attached to the harness, after changing it out, I have been fault free now for a week.

I hope this helps someone like this site has helped me.

Dave


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 Thanks given by: hookliftpete , Rawze , schISM
08-13-2022, (Subject: Fault 125 intake manifold 1 pressure ) 
Post: #2
RE: Fault 125 intake manifold 1 pressure
yeah, thanks for sharing this.

The barro sensor is often overlooked when ghost issues occur. It can cause operating mode changes to happen when they are not supposed to, it can cause improper combustion and fuel-air-mix, and it can cause false alarms for other sensors, as the barro sensor is used as a comparison sometimes to see if other sensors are in reading in-range or not.


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