Dtc 33

[piersbc]

This is the code that showed up after an hour drive in 100 degree weather with the A/C going the whole time. My research shows that it means EGR Control Pressure/Baro Sensor Circuit High. I did a search but didn't come up with anything. The engine light is off now...it only came on for a few seconds...is this anything to worry about??

[More Power]

A "circuit high" indication means the PCM is detecting an abnormally high voltage level coming from the baro sensor. Bad wire, bad ground, loose connector (either at the baro or PCM), or bad sensor could cause this. High heat might be a contributing factor in an overly sensitive (read abnormal) baro sensor.

Jim

[piersbc]

so where/what is the baro sensor?

[Warren96]

Mine does the same thing! Hot weather,AC on,at least a half hour of highway driving.A DTC 33 means that the EGR could be receiving insufficient vacum, or like ''More Power'' said a poor baro sensor.According to the GM service manual under these conditions the PCM will shut off the EGR.It could also be a leaky vacum hose,or a bad pump.Mine has odd vacum readings from the pump.When you start it cold the readings are steady as it warms up at a stop it becomes very shaky.Since the service manual say's that the PCM shuts off the EGR i dont feel an urgent need to be alarmed.Did you change the vacum lines? That is the best place to start.

[JohnC]

My experience is that the egr and wastegate solenoids first fail under extreme temperatures. My guess is that's what's happening. EGR problems are pretty beneign as the PCM just turns the EGR off when it happens.

[piersbc]

Thanks for the replies...I'll see if it happens again. If it does I'll check the vacuum lines and pump and selenoids and sensor. This may be a good reason to get rid of the vacuum pump anyway.

[Warren96]

Then you have to buy the Turbomaster to start then a shorter fan belt and a different belt tensioner and what about all the codes it will be setting with no vacum circuit? Another 'Puter? In my area the truck wont go thru state inspection with the SES light glaring on the dash.