I have a 1998 Saturn SC2 that shows a P0446 CEL code. I have replaced the selenoid and visually checked the hoses for crakes/leaks etc..... but the light continues to turn back on. What else should I look for? It appears the light "usually" turns on when I've been sitting, engine off, and the key on "ACC" to listen to the radio or such. It never comes on (after turning it off) while driving and there are no drivability issues.

Likely a restriction in the EVAP vent tube (which is the top pipe coming out of the charcoal canister (black box behind the gastank) Has your gas tank been filling slowly or has the gaspump been shutting off prematurely at the station?

Possible sticking EVAP vent solenoid valve (Hard to test without a scan tool to command it open and closed)

Unlikely a bad charcoal canister but possible.

I did replace the solenoid and the light came back on again within 30 minutes...... it seems to only come on after I've had the key in the "ACC" position (ie...listening to the radio while waiting). I'll check the lines back to the canister this evening.

Ok, keep us posted.

Any chance that the 446 code could be set by a problematic gas cap? That'* easier to try than dropping the tank to get at all the hoses and the canister.

P0446

Description
EVAP SYSTEM CANISTER VENT BLOCKED


Evaporative (EVAP) emission system includes following
components: fuel tank, EVAP vent solenoid, fuel tank pressure sensor,
fuel pipes and hoses, vapor lines, fuel cap, EVAP emission canister,
purge lines, and EVAP purge solenoid.
Symptoms
You likely won't notice any drivability problems.

Causes

• Normal EVAP system operation is commanded (EVAP vent solenoid
  open, EVAP purge solenoid normal).

Solutions

• Check if vent hose is between EVAP canister and EVAP
  solenoid is kinked, pinched or blocked.
• For missing or damaged "O" rings at EVAP canister fuel vapor
  and purge line fittings.
• Check for damaged harness.
• Replace EVAP vent solenoid.
• Replace EVAP canister.

Ok, here is what I've done. I ran a smoke test on the vac system with no signs of problems. I've replaced the Vent Solenoid, the Purge Valve, the Canister, and even for good measure the fuel cap, and still have the DTC P0446 coming back. The only thing I have not done is replace the fuel tank pressure sensor. Could this possible be the issue? What else should I consider?

thats when being able to use a two way becomes very handy, the circuit from the pcm to the vent valve could be bad, i would think second would be the sensor maybe, it is how the tank sees the vacuum.

Here'* an update....fixed problem a few weeks ago..... we put a MODIS on it along with smoke test. No matter if we turned vent solenoid on or off we had smoke from the vent.... I had just replaced the vent valve..... we grabbed hold to the pig tail wire attached to the vent valve and wiggled it....WA-LA....on and off, on and off............ we pulled the pig tail apart and got the needle nose and squeezed the connectors a bit....took a few tries as we didn't want to damage the connectors..... got it....fixed the problem and no CEL now in about a month!

thank you for updating the fix