I have a 2004 GMC Sierra 1500 base with the 5.3 liter vortec and 98,000 miles. I had this code come up before. I changed the vapor canister purge solenoid under the hood, the vapor canister vent valve/solenoid by the fuel tank, the fuel tank pressure sensor on the top of fuel tank, AND the fuel fill cap. These are ALL of the components that I have found that could possibly be associated with the P0446 code. After about 6 months and very little mileage, maybe 1,500 miles ( I don't drive vehicle very often do to fuel prices) the check engine light came back on and BAMM... P0446 code AGAIN! Is this just a poor engineering problem!? The parts I replaced were all ACDelco OEM components. They could NOT have gone bad already!!! I am honestly fed up with it! Truck runs and drives great! Think this is an instance that calls for some black tape over the check engine light and forget about it! Lol If anyone has ANY other possible reasons for this code, please share!
If you have high end scanner, try looking at your fuel tank pressure reading along with fuel tank pressure voltage. With key on and off, you should be reading between 1.4 to 1.6 Volts and close to atmospheric pressure of 0 inches of water.
I have the same code on my 2001 GMC Sierra 1500 W/4.8L V-8... When I bought it, on day 1 I had the code read and was recommended to get a new gas cap. I was told that that should solve the issue.... Bought a new cap and nothing changed whatsoever.... Now I have to run the hawg through D.E.Q. and that code is causing me to fail immediately... Not sure where to go from there?.... ANY ADVICE ANYONE???
On these GM vehicles a faulty fuel pressure sensor can cause this code to trigger. If you have a volt meter in hand, back probe the signal wire to the sensor. It's usually the middle wire of the three wire connector. With key on engine off it should read approximately 1.4 - 1.6 volts.
I have a 2004 GMC Sierra 1500 base with the 5.3 liter vortec and 98,000 miles. I had this code come up before. I changed the vapor canister purge solenoid under the hood, the vapor canister vent valve/solenoid by the fuel tank, the fuel tank pressure sensor on the top of fuel tank, AND the fuel fill cap. These are ALL of the components that I have found that could possibly be associated with the P0446 code. After about 6 months and very little mileage, maybe 1,500 miles ( I don't drive vehicle very often do to fuel prices) the check engine light came back on and BAMM... P0446 code AGAIN! Is this just a poor engineering problem!? The parts I replaced were all ACDelco OEM components. They could NOT have gone bad already!!! I am honestly fed up with it! Truck runs and drives great! Think this is an instance that calls for some black tape over the check engine light and forget about it! Lol If anyone has ANY other possible reasons for this code, please share!
One other area of concern can be the fuel pump oring gasket, creating a very small leak.
If you have high end scanner, try looking at your fuel tank pressure reading along with fuel tank pressure voltage. With key on and off, you should be reading between 1.4 to 1.6 Volts and close to atmospheric pressure of 0 inches of water.
I have the same code on my 2001 GMC Sierra 1500 W/4.8L V-8... When I bought it, on day 1 I had the code read and was recommended to get a new gas cap. I was told that that should solve the issue.... Bought a new cap and nothing changed whatsoever.... Now I have to run the hawg through D.E.Q. and that code is causing me to fail immediately... Not sure where to go from there?.... ANY ADVICE ANYONE???
On these GM vehicles a faulty fuel pressure sensor can cause this code to trigger. If you have a volt meter in hand, back probe the signal wire to the sensor. It's usually the middle wire of the three wire connector. With key on engine off it should read approximately 1.4 - 1.6 volts.
The easiest way to check is with a capable scanner that gives you the voltage pid to the sensor.