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+--- Thread: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure (/showthread.php?tid=10268)
ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - OakleyRiver - 08-19-2025
Hello, searched around and did not have much luck on this topic.
Cummins ISX CM2350 ESN 79950919.
It is in a 2017 Kenworth T800, Single air breather.
Check engine will come on and off through out a weeks time. Only codes ever in it are 2346 Turbocharger turbine intake temperature data valid but above normal operating range. 6725 Intake manifold 1 pressure data valid but above normal operating range. Went through Cummins diagnostics and found a few things. Had a few charge air cooler leaks and boots leaking. Replaced, repaired and confirmed no more leaks from turbo outlet to cylinder head. Replaced both sensors, intake sensor was very full of carbon build up. Updated ECM to lastest file and sent it back out. Ran a few days and then came back on again for same codes. Both codes are very close in time stamp. Looked through and did not see anything alarming. Pulled intake manifold sensor again and it was still very clean. Did find someone on here that had a issues with barometric pressure sensor so I replaced that also. Sent it back out and at end of the day if came back on. Inspected wiring harness and it do not see any rub areas. Those two sensors and run by separate wires, no common wire between the two. Any one fight this battle before or have anything specific to look for? Thanks.
Let me know if there is any more info I can provide. Trying to be as clear as possible, Thanks for the Help!
RE: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - marek4792 - 08-19-2025
Intake restriction from a crap air filter/aftermarket CAC will definitely set those codes. Is the exhaust pressure passage completely clear of carbon packing?? EGR Tune-up done??
RE: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - tree98 - 08-19-2025
Hook up insite and key on engine OFF look to see if insite shows the turbo spinning.
The turbo speed sensors can get cooked from drivers lugging the dog shi#t out of the engine. When this happens the sensor doesn't show zero movement. Instead it shows the wrong speeds so the ECM is getting incorrect data and isn't able to control the turbo correctly. This leads to the symptoms you mentioned.
RE: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - OakleyRiver - 08-20-2025
(08-19-2025 )marek4792 Wrote: Intake restriction from a crap air filter/aftermarket CAC will definitely set those codes. Is the exhaust pressure passage completely clear of carbon packing?? EGR Tune-up done??
Air filter is clean, in good condition and was replaced about 5,000 miles before this, CAC we installed was not a cheap one. Is an aftermarket but good quality. I did replace back pressure sensor but not the Delta P Sensor, I will do that today. Did clean the passage way for exhaust back pressure sensor.
RE: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - OakleyRiver - 08-20-2025
(08-19-2025 )tree98 Wrote: Hook up insite and key on engine OFF look to see if insite shows the turbo spinning.
The turbo speed sensors can get cooked from drivers lugging the dog shi#t out of the engine. When this happens the sensor doesn't show zero movement. Instead it shows the wrong speeds so the ECM is getting incorrect data and isn't able to control the turbo correctly. This leads to the symptoms you mentioned.
Insite shows 0 on the turbo speed but truck ran all day yesterday without an issue and no codes. It sat overnight so its cold this morning but ill try and get it to throw the codes again and check turbo speed at that point when everything is hot.
RE: ISX Codes 2346 Turbo Intake Temp and 6725 Intake Manifold Pressure - OakleyRiver - 08-20-2025
Thank you to those that helped. I believe we have found the problem. I did finish up the EGR tune up by replacing Delta P sensor and Exhaust back pressure, also double checked to make sure the tube was cleaned, it was. Test drove truck for 30 miles and did not get a code to come back but did notice turbo speed seemed to be bouncing around more that I think it should. After idling for a minute I noticed turbo speed was bouncing from 4,500 to 14,000 RPM. VGT commanded was changing by only a percent or two along with this. Decided to replace speed sensor and try again. Now turbo speed at idle is 19,330 to 19,750 RPM. I'm going to assume this was the issue and send the truck back out. Thanks for the help! Hope this helps someone else along the way.