i would say you have a vacuum issue. either you have a crimped line going to the turbo boost solenoid or the vacuum pump is not creating enough vacuum for the system. Dave is right that there may not be anything wrong with the system when you rev it in your driveway or see smoke under heavy acceleration on the freeway. the only time that code will set is when engine speed is greater than 2400 RPM,fuel rate is greater than 20 MM
Boost pressure less than or equal to 20 KPA from desired (internal to PCM) Which means that you would need to be driving for this code to be set. the flow chart said either vacuum issue or the turbo boost solenoid most likely would be the problem.

 

Thanks.
I ordered a $39.95 solenoid from SSDiesel on their advice and hope this will solve the problem.
Next week I will post as to the outcome of this brief-I hope-adventure of an H1 owner.

 

Has this concern been resolved? If you are still feeling that this is a concern, I would recommend contacting your local dealership for more information. Please feel free to keep me posted. Thank you in advance.

Tricia, GM Customer Service.

 

Oh geez, which local GM dealership would you recommend he took his H1 to Peggy? Especially since most won't touch it.

 

Yeah, keep Peggy posted so she can do what? NOTHING!

 

hey Dave, should i change my user name to CERTIFIED AM GENERAL H1 SERVICE TECH???
NA, to long....

 

LOL. Maybe you should Mike. Tricia/Peggy has been offering non-advice on numerous forums. Basically it is give me your VIN and go to a local GM dealer. So far, to my knowledge, GM has not honored a single warranty claim she has referred. Besides the generic go to your local dealer she is useless. Since most dealers aren't authorized to do service work on Hummers it would at least be moderately helpful if she could direct people to the closest authorized service center.

 

Thanks Peggy/Tricia for your imput. However we have no GM dealership on this island and, from the other folks offering me specific and helpful information, I will respectfully pass on your suggestion.

 

Sorry to bump the thread, but here's a little help for people experiencing this problem. I had the exact same code with the same symptoms. "P0236 - Turbo/Super Charger Boost Sensor A Circuit Range/Performance".

I noticed acceleration was a little slower than normal, but not a whole lot different. Some people might not even notice it. Upon merging on the highway at around 50mph, you might get 100% engine load and it doesn't seem to want to accelerate any further. This can be seen if you are using a ScanGauge or TorqueApp. You'll also get a little black smoke from the tailpipe. The engine is just starved of oxygen. It doesn't hurt it, but it isn't optimal and fuel mileage will drop.

I started with replacing the boost solenoid valve because it is the cheapest and easiest fix. For me, that did not solve the problem.

I then noticed that I had a crack in my vacuum line that went from the top of the vacuum pump to the boost solenoid valve. I ordered the line from HPG and tried to replace it without removing the vacuum pump, but I couldn't reach the fitting easily to put the new one on.

I ended up removing my vacuum pump, only to realize the bottom cap seal was blown out of the vacuum pump. I replaced the vacuum pump and the hose going to the boost solenoid valve and that solved my problem. The fault code immediate cleared when I fired it up and I can now hear the turbo whine upon acceleration, with no more black smoke. Fuel mileage is a few mpg better on the highway, and engine load has decreased. At 65mph, I'm around 51% load, whereas before with the bad vacuum pump it was around 60% load at 65mph.