Your Chevy's P0452 trouble code indicates a problem with the Fuel Tank Pressure Sensor. The first thing we recommend doing is ensuring your Silverado's gas cap is secure and driving your truck for 100 miles to see if the light will turn off. The Fuel Tank Pressure Sensor senses changes in the fuel tank pressure or vacuum. If at any time your trucks gas cap is loose, trouble code P0452 will be detected.
If you've ensured the gas cap is not the problem. Inspect the Fuel Tank Pressure Sensor's wiring harness. The fuel tank pressure sensor signal voltage to the ECM (engine control module) varies from 0.1 volts with pressure in the fuel tank to above 4.0 volts with a high vacuum in the fuel tank. If the harness is disconnected or the sensor wires frayed, a trouble code P0452 will be triggered.
Finally after inspecting the the gas cap, and the wiring harness/wires, you should inspect the Fuel Tank Pressure Sensor itself. The fuel tank pressure sensor is located at the gas tank near the sending unit.
P0452 will be set when the fuel tank pressure sensor voltage reads less than 0.1 volt for more than 5 seconds when your Chevy Silverado's ignition switch is in the run position. If the sensor is found to be defective, replace it, clear the ECU trouble codes, and drive your truck for approximately 200 miles in order to "complete" the emission monitors. Your truck will then be ready for a smog check retest. A new aftermarket Fuel Tank Pressure Sensor will cost around $65.00.
Two additional emission components which should be inspected on your Chevy Silverado are the The EVAP canister vent solenoid and the EVAP canister purge solenoid. Both these solenoid valves must be working properly in order to seal the gas tank during the Fuel Pressure Test. Specifically, if the EVAP canister vent solenoid is stuck open, the system will not be able to pressurize the gas tank in order to test the EVAP system and the Fuel Tank Pressure Sensors voltage readings will be inaccurate. Theoretically if either the EVAP canister vent solenoid or the EVAP canister purge solenoid valve are defective a trouble code DTC P0442 or DTC P0446 should be set, however this will not always be the case, so it's best to inspect these components regardless of whether a DTC (digital trouble code) for them exists.
