Set codes while towing

[Jcolg]

This weekend was my first opportunity to tow with the truck. I tow a 22' 5'th wheel which weights 4400 lbs dry, loaded with our stuff it's probably pushing 6000 lbs. The trip this weekend was to a campground about 100 miles away. On the trip out on Friday the truck ran great and the SES light did not come on. On the way back on Sunday about 30 miles from home, I stopped at a truck stop to top up. The ramp getting back on the highway was the beginning of a long up hill grade and I had to step on it pretty good to get up the speed. Before I reached the top of the hill the engine icon came on. I thought at the time the truck might have felt a little lazy, however it was a long grade and I'm still not sure what is normal for this truck. Anyway it still seemed to be working fine all the way home. When I got home I read the following codes: P0101 (Mass or Volume circuit range performance problem), the truck had set this code last week while not towing, it went away by itself and I have not had a chance to pull the sensor to inspect it, however I will later today. The second code was P0236 (Turbo boost Sensor A circuit range/performance) and the last was P1406 (EGR Valve Pintle position circuit). Any help interpurting these codes would be appreciated. It looks like I might have multiple problems or maybe there is a comman cause. BTW I did not see any black smoke during any of this, and the mileage while pulling was 15 mpg (imperial Gallons), Thanks.

[Jcolg]

Update - After looking further I began to suspect a problem with my trucks vac system. I made up a vac guage and made some measurements. First I measured the vac coming out of the pump. At idle there was a steady 25 inches/Hg, which I think is probably OK. Next I T'ed into the vac line that runs to the top of the turbo. This vac was 11 inches at idle (steady) and it increased slightly and bounced around a bit as I reved the engine. The last place I checked was at the EGR valve line. Again I T'ed into that line and I observed different readings at different times. Sometimes at startup there would be 0 inches there for about 10 seconds, then the vac would build and jump around between 0 and 10 inches. Sometimes it would steady out at around 4 inches, and other times it would disappear altogether. I noticed that this line is T'ed into a sensor mounted on the firewall (map sensor?). I'm thinking that these fluctuating readingss are not normal. Could anyone tell me if they know what the normal vac readings should be at these points and suggest what parts I should consider changing? I'm thinking I probably need to replace 1 of the 3 solenoids and possibly the Map sensor? Thanks

[nvmtnlion]

I had alot of the same symptoms you are describing and the vacuum gauge readings. I got fooling with the wires that go to the EGR solenoids. When I would move the wires, the vacuum would shoot up to ~20. I peeled back back the loom and found that the wires to the EGR vent solenoid were worn through the insulation and touching intermittently. You might want to check the same.