P0446 code

KE7VMY

MEMBER
2000 CADILLAC SEVILLE
4.6L
V8
2WD
AUTOMATIC
90,000 MILES

Where should I look first?

Tuesday, February 26th, 2019 AT 8:32 PM

4 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

This could be a plugged or full charcoal canister in your Evaporative Emissions (EVAP). This system is part of your vehicle's emissions control system and works by collecting and then purging fuel vapors into the combustion process via the throttle body. Fuel vapors are collected and stored in a charcoal canister. When this canister fails the Power-train Control Module (PCM) AKA, "computer" will set Direct Trouble Code (DTC) P0446.
I have included in the diagrams below a step by step troubleshooting guide for this DTC, Please go through it and get back to us with what you find out.

Thanks,
Alex
2CarPros

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Tuesday, February 26th, 2019 AT 9:29 PM

JIS001

MECHANIC
3,408 POSTS

I would recommend you get an EVAP smoker. Disconnect the purge valve hose to the tank and smoke it. If smoke comes out the vent then your fuel tank pressure sensor is bad. If no smoke comes out then check for a stuck closed vent valve or a spider nest build up at the vent tube.

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Tuesday, February 26th, 2019 AT 10:52 PM

KE7VMY

MEMBER
2 POSTS

The vent solenoid was sticking and I applied 12 volts AC to it to cycle it and it cleared it up for now so I can get the emission test done a then after that I will get a new solenoid. My tabs run out on the 28th so I was in a sweat to get the problem fixed. Many thanks for all your help, you guys are great.

Bill T.

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Wednesday, February 27th, 2019 AT 2:21 PM

JIS001