P0452 is the code for Fuel Tank Pressure Sensor Circuit Low Voltage. The only possible causes of this code are a faulty FTP Sensor, faulty ECM, or a wiring problem between the FTP Sensor and the ECM. Here is a link to the GM service manual for that code. Hope it helps!
http://gsi.xw.gm.com/si/showDoc.do?d...=Jun+1%2C+2010