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Rawze

(07-30-2017 )zyNoT Wrote: I also wanted to add that a fellow driver at a truck stop mentioned to me that he took his truck to peterbilt because he got freaked out when it prevented regens because of the derate code that eventually comes along with the codes I listed above if the problem isn't fixed in a timely manner. I will say this, peterbilt said he needed a new turbo, said his intake manifold needed torn apart to clean it out (which is possible, but unlikely). The costs of labor he was quoted was around $4k. I mentioned to him to replace the turbo speed sensor. He did, called me back and said no more problems. Cost him about $120 for the sensor and about $80 for labor. Much better than $4k. Hope this helps someone else as this is a common problem on the CM2250s over 500k mileage.

The ISX has an optional programming setting for the turbo speed sensor where if it fails, the ECM is allowed to calculate its speed instead of throwing a code. Some trucks have this turned on, some do not. It is NOT adjustable in Insite.

I had a Peterbilt truck (CM2250) here once that dropped fuel mileage and basically ran like crap with no explanation. Guy had it to 4 places and no one could find out why it dropped fuel mileage and had other ghost issues. i was looking at the data at idle, and the turbo speed was not moving/jumping around like they normally do. It also was not at zero. I had the guy rev the engine up, and the speed did not change at all, yet you could hear the turbo speed up slightly. Rev the motor up high, and the speed changed.

I went in and disabled the option to calculate turbo speed and sure enough, the thing threw a fault for turbo speed, as it was reading zero. Oddly enough, above about 25k rpm, the speed sensor started working, but was an incorrect reading. - $300 bucks later from the stealershit and the truck ran very well again and the speed sensor worked perfectly with the "calculation upon failure" option turned off.