Two TDC come & go

[GaryHayes]

Gentlemen: Here's the tune. My Dodge 2010 3500 duallly 174,K mi. manual tran. intermittently throws out code PO299 and PO49D, 'manifold pressure sensor out of range' and 'EGR control position exceeds learning limit' respectively. They first appeared after ascending a long grade pulling a 25' travel trailer, (7000 lb) up the Sierra's, then down grade with exhaust brake engaged approx. 8 mi.
After driving 150 highway mi. @ 60 mph, ck engine light off.
Again, after an assention, then downgrade with exhaust brake, both codes reappear. Drive on straight away at highway speeds, TDC code disappear. Hey, no worries, right??
This all happened in Oct. Been making unloaded runs into town, run around town. driving slow, lots of idling , regen cycles more common. Just what it is expected to do.
Then, yesterday, up to the top of the mountain, no pulling, almost empty, come down the mountain same day, exhaust brake engaged often, 300 mi round trip . and Bang, get the codes again. What the...?
And I get a change oil on evc with only 3800 mi. on the last change. Another 'what the...?
Got new CCV and EGR & EGR cooler serviced 15K mi ago.
This truck runs good, decent millage. No loss of power I can detect.
Could these codes indicate a turbo-sooting up problem? egr problem? Just checking with you guys in the know before it goes to dealer. And thanks in advance.

 

[sag2]

I have not seen it on a diesel, but I used to run into it on gas vehicles that would set a similar code coming down the grapevine. Engineering sent me there to collect some data on a rental car company that was getting it on some of their rental cars. It turned out if you went all the way down the grapevine to the north and never touched the throttle it would throw manifold leak code (no similar code on diesel) because the MAP sensor would only update if you got on the throttle 70% or greater. Could be something similar from the Barometric pressure change going down the mountain.

 

[GaryHayes]

I have not seen it on a diesel, but I used to run into it on gas vehicles that would set a similar code coming down the grapevine. Engineering sent me there to collect some data on a rental car company that was getting it on some of their rental cars. It turned out if you went all the way down the grapevine to the north and never touched the throttle it would throw manifold leak code (no similar code on diesel) because the MAP sensor would only update if you got on the throttle 70% or greater. Could be something similar from the Barometric pressure change going down the mountain.

Hey thanks, Sag: Still don't know. I'll tear out the egr valve . do a visual Could be lose electrical connection.