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SS Specific Service Issues/RepairsService/Repairs specific to the SS. Turbo-Brembo Brakes-2.0 Engine-Limited Slip Differential-Programmable Display-MU3 Transmission
I have a 2008 HHR SS with 154000 on it. I bought it with 79000 on it. I changed the MAF sensor with a GM pn 15865791 and a new correct GM throttle body. Ever since I get codes P2178,P0101 and P0299. I have went over everything I can think of looking for boost or vacuum leaks and can find none. Is there a learn process for the throttle body or MAF sensor? The check engine light keeps coming back and my mileage is lower by about 3 mpg. I am at a loss and need to pass emissions to get new plates. Really don't know where to look next. Thanks for any help!
Do you have an oiled air filter, or when was the filter last changed? More than once, a new filter made the p0101 go away.
Check the wiring connector for the MAF sensor, there may be a damaged wire. I had a damaged wire once.
Remove the negative battery cable from the battery, then remove the ECM connectors from the ECM. Then clean the connectors. This last time there was sand in the connectors.
They all have something to do with long term fuel trim. The P0101 disables boost control. causing P0299. The P2178 is fuel trim rich at cruise or accel; more fuel than boost. All are related.
The most common cause of P0101 is an over oiled air filter or dirty MAF.
Every time the p0101 would even go pending, not yet lighting the CEL, I felt the turbo drop out. Never got a p0299 though, not even when it set hard and lit the CEL.
Does the car have the stock or a modified intake? What led to changing the MAF sensor? Did you have the problem before you changed it? Do the still have the old one? Have you carefully checked the wiring and connector pins?
You could try cleaning the new MAF sensor or cleaning and reinstalling the old one. Even a bit of lint will cause bad readings.
Stock Wix air filter. I usually change it every other oil change. Its due so I will try that. The boost does drop out. Only makes about 12 lbs. If I push it every gear it will drop out for sure. I have changed MAF sensor, map sensor in the charge pipe, wastegate and boost sensor, bypass solenoid, throttle body. The vacuum tank and the blow-off both hold vacuum so no leaks there. All the parts are GM. I changed the throttle body because it needed cleaning and its such a PITA to get to I wasn't taking chances with it. Appreciate the help!
to the forums! 
