check engine light

UPDATE!!! Problem fixed!!!!! All it was?
Bad turbo speed sensor!!

 

Expensive little sensor huh!

 

I'm having similar problem asking for thoughts . So a bit more in depth . I changed the turbo speed sensor but it's still dropping boost. Then I decel and reapply and the boost is there but will drop again which throws the amber check engine light. But I can use my Jakes and check engine light doesn't come on . Boost drop is only roughly 3-5 psi but is just enough to throw light on . Ie. Max throttle boost is 30-31 but will fall to 26-27. Half throttle 23-26 drops to 16-20

 

I having about the same problem I have a 06 freightliner century with a remanufactured engine that was installed new May of 2011 I just had it at the freightliner in Montgomery,AL had a bad water pump this got replaced along with a big hose bottom of the radiator and connects to the water pump they check to see why the check engine light comes on climbing a hill
A code for a bad VPOD show up so they replaced this with the wiring harness and a boost sensor and as I was going north on I-65 with a heavy load of roll paper the check engine light came on again I call this shop they said to come back they check it out they found out the Delta pressure sensor for the EGR was bad and they replace it that was last Friday
Now this morning in Tennessee on
I-65 north of exit 22 on a long hill climb the check engine light came on again and more this afternoon as I was coming back to Montgomery,AL with a load of bale cardboard
And as I climb a long hill the check engine light came on this time stay on almost a minute each time and it came on almost every hill
Only when the coolant temperature at or higher than 200 and RPM at or more than 1700 and mostly in 9th gear
Now it has came on in 7th ,8th, and 10th gears few times came on when I'm not going up a hill I was driving on flat road in 10th gear
And the other day as I was bobtailing home the check engine light only came on when my speed was around
75 MPH and my foot on the pedal when I let off the throttle the check engine light went out
I don't know what it could be
The freightliner shop has checked it out 2 times that was last week
I'm thinking the exhaust temperature getting too hot
I like to know what I need to do to fix the problem