Buick Repair Questions? Ask a Mechanic for Answers ASAP
The most common cause of a p0446 on this car is a faulty fuel tank pressure sensor.
Check the tank pressure value with the fuel cap and the evaporative vent hose removed from the evaporative canister- you will need a scan tool for this.Check the fuel tank pressure sensor voltages on the Gray to Black and Dark Green to Black, sensor connected and key on- you will need a multimeter for this.Should have near 5.0v from the Gray to the Black.Should have near 1.5v from the Dark Green to the Black.
Here is how you get to the sensor. No dropping the tank or lift required.