2001 Tahoe check engine light

[2001 5.3]

I have a 2001 Tahoe 5.3 LT and once every week and a half I get a check engine light and it throws a code p0446 but the scanner picks the code up twice. I have tried replacing the aftermarket gas cap with a factory one and that didn't help. Does anyone have any ideas? Truck runs fine even with light on

 

[autoexpert]

The check engine light is also known as malfunction indicator lamp (MIL). It shows when having a glitch in the electronic control module of vehicles. Commonly, the check engine light is positioned within the instrument console. In some older vehicles, the check engine light was referred to as "engine" or "trouble", which demonstrated small problems including overheating or flat oil pressure inside the motor. The check engine light is usually of golden or reddish color, and there are two types of it:

Read detailed article here : http://checkenginecode.com/flashing_check_engine.html

 

[rockenthebowtie]

The P0446 EVAPORATIVE EMISSIONS VENT PERFORMANCE.. Dont know if you have access to a scan tool with data display but usually a vent perfomance issue is do to the fuel tank pressure sensor sending a voltage signal to the PCM indicating there is a problem in the evaporative system and the pressures in the fuel tank isnt changing during a vent or vaccum seal test event.. and it can be anything from a bad vent solenoid. Purge solenoid.. a Charcol canister and or even a shorted fuel tank pressure sensor itself but that why you need to see data

 

[rockenthebowtie]

Oh by the way for the most part SES light is only illuminated by the PCM thru the ground circuit of the the SERVICE ENGINE SOON lamp circuitry only when a emissions cotrol failure is detected thru the strategic placement of various sensors on the engine.. air intake.. and exhaust system