Altitude pressure sensor

Hello: I'm new to this forum, so forgive me if I'm in the wrong place. I have an 07 Chev 6.6 TD Duramax/Allison. I've had trouble in the past when going up high altitudes. The engine light comes on and stays on for quite awhile. After which, it goes off without coming on again. How ever Last year, It went on and the truck lost power and went into some kind of mode that would only let me go about 10 miles an hour. I was pulling my 5er so I pulled over, called On-Star and they told to me to turn the engine off and wait a few minutes. I did and sure enough the light went off and I continued my trip. When I got back, I took it to the dealer and they replace some sort of sensor. I hadn't taken the truck up any high places until a couple months ago, and then the light came on again but the truck ran fine. Got to the campground and the next morning the light was off and it never came on again. So my question is: Has this ever happened to anyone else? Should I take it back to the dealer. I there something else that can cause this problem? We're planning a trip up to Yellowstone in summer and I know i"ll be climbing some mountains, so I want to make sure I'm ok.
Thanks in advance for your help
Manny

Welcome to TDP

Sounds like your running up and down Hwy 395. Nice grade climbing north out of Bishop.

Have you pulled the codes to see what the problem is?

Either a good code scanner or a trip to parts store to see if they can read them. Get those and come back I bet you will get lots of help here.

Yep, got that right. up the 395 seems to happen right after I stop for fuel in Pearsonville. I guess the incline starts about there..I'll give your suggestion a try and get back to you.
thanks a lot
Manny

The atmospheric pressure sensor is on the side of the ECM. You could look and make sure it's not blocked with something preventing the ECM from seeing pressure changes. If it's bad I would think you would need to replace the ECM to fix it.

Jay

OK... NOW...what's an ECM?

The computer for the engine. Engine Control Module

Jay

Have you checked to see what codes are being set? Beartooth Pass on US-212 in Yellowstone crests at nearly 11,000'.

Thanks everyone for the input.. I called the Chev Dealer and asked about this problem and I was told that there's no way of checking it unless the check engine light is on... Does that sound right to you guys?