What does an obd11 code of po446 mean on a 2000 chevy silverado 1500?

Question edited for clarity
Question moved to model category.

Help in the link, under seat looks like the best solution.

https://www.google.com/search?q=2000+Chevy+Silverado+1500+EXT+Cab+Best+box+specs+for+single+1100w+10+ported

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Check the switch that is under the dash on the brake pedal arm.

Drive by wire throttle correlation ... There are problems with a small yellow wire that breaks going into the harness plug at the throttle body. keep me posted but check that first.
Ron

Hi, a P0446 means Evaporative Emission Control System Vent Control Circuit Malfunction

Full details @ http://www.obd-codes.com/p0446

I am by no means an expert but I had the same issue with my 2000 chevy 1500. I bought a new 4x4 switch from the dealer for about $70; it just pops out and back in; it completely fixed the problem including the fact that it would not kick out of 4 wheel drive. Apparently the switch is a very common problem with this make and model.

third back pass side the coil is probably bad if you have a miss code common problem

go to www.troublecodes.net and look up the codes.

if the cat was pluggin you would see this as your going down the road it would not get to top speed .. They act up usually only run 40 top speed.

the shifter accuator or the wires going to it on the transfercase..gl

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

The vehicle control module (VCM) monitors the performance of the evaporative emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system and monitors the vacuum decay rate. The VCM sets this diagnostic trouble code (DTC) if the vacuum decay rate is more than a predetermined value. The VCM monitors the amount of vacuum and the amount of pressure in the EVAP system by monitoring the fuel tank pressure sensor. For this DTC, the VCM turns ON both the EVAP purge valve and the EVAP vent valve when the Conditions for Running the DTC are met. This applies an engine vacuum to a closed EVAP system. The VCM turns OFF both the EVAP purge valve and the EVAP vent valve when the system reaches a correct amount of vacuum. The EVAP system should quickly RELEASE the vacuum in the EVAP system with the EVAP purge valve OFF and the EVAP vent valve OFF (open). This test indicates a blocked or restricted EVAP vent path if the EVAP system fails to release the vacuum quickly enough.