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Q: 2001 pontiac grand prix gt PO446 code how do i fix it? what else do i change? on 2001 Pontiac Grand Prix

what else could cause this light to come on i have changed the purge valve under the hod changed the vent valve in the wheel well checked all the lines they look good i dont think i have a bad pcm but if i did what would i check before i take the pcm out and get a new one i was told the canister but idk if thats the issue i never hade this issue before it just happende a few months ago and my inspection is over due.................. HELP!!!!!!!!
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1. Install a scan tool and look for the fuel tank pressure sensor voltage reading.

2. With the key off, remove the gas cap then turn the key on and check voltage. It should be 1.3-1.7 volts.

3. If not in that range, check the wires to the sensor and make sure it has a good 5 volt reference on the Gray wire and ground on the Black.

4. Check the Dark Green wire back to the Powertrain Control Module (PCM) for opens or shorts.

5. Check the vent solenoid for plugged up. Remove the hose going to it and see if can blow through the solenoid easily.
Tech Tips:
If this sensor is off from the beginning, when it runs the test it will not see the change it is looking for, even though the rest of the system is functioning correctly. It may not set a code for that sensor out of range unless it goes to an extreme value.
Go to and spend the $26.95 to get any info you need on your car for a whole year. This is factory info. Not haynes manual or junk info. You can get your answer there.
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