I have a 2001 Chevy Suburban 1500 4WD. About a year and half ago I dropped the gas tank to replace the fuel pump unit. I got the new unit (FTPS included) and finished the job. About 2 months after that job I got OBDII code of P0452 (Evaporative Emission Control System Pressure Sensor Low Input), it would not erase, but since it didn't affect the engine, I did not mess with it. Now it is time to inspect and of course it will not pass emmisions. Usually the P0452 code appears twice when I scan the system after a few weeks, but sometimes a P0453 code gets thrown up (same as other but high input at the FTPS). The FTPS is on top of tank and in order to check or replace I need to drop tank again (don't want to do it, if I don't have too). The other potensial components could be the canister, itself or the vent solenoid or purge solenoid or any of the hoses. When the P0452 code is thrown is it almost always a bad or badly connected FTPS? Any help or tips would be greatly appreciated!