P0446 code and Fuel Cap
 

About a week ago, my 1998 Bosxter w/97,000 miles displayed a check engine light which my OBD2 reader displayed a P0446 code.

I've read that one of the first items to check is the fuel filler cap. To my knowledge, my cap is original, making it 25 years old. So I removed the cap, checked the O-ring in the cap and it looked dry with a number of barely visible tiny "hairline cracks" but no missing sections.

As a "test", I cleaned the metal filler neck where the fuel cap mates to it (lots of black stuff rubbed off), lubricated the cap's O-ring with oil and made sure the cap was very securely tightened much harder than just the first "click sound". Then I resent the code with my OBD2 reader which obviously extinguished the check engine light.

I then drove the car for a couple of days until the OBD2 reader indicated that all car's monitors were in the ready state........since all sensors were "ready", I have driven about 250 more miles over 4 days, in urban areas and on highways.....the check engine light has not returned.

Hoping that the gas cap was the issue, I ordered a new cap, which should arrive in a few days.

Do you think I solved the problem?
(as an aside note I was in the habit of really topping off my fuel tank beyond the pump's auto shut off....otherwise the panel gauge never indicates truly "full"....I think I'll end that practice too.)

New cap is arriving today....but since the error code first appeared I lubricated the cap's o-ring and firmly tightened it......so far no more check engine codes.....so I'm assuming it was the cap seal all along....new cap comes today.

P0446 is the code indicating that the purge airline going to the EVAP canister is blocked or restricted.

Outcome.......as suggested the FIRST, EASIEST, CHEAPEST solution worked!

NEW FUEL CAP.........$14 and a couple of weeks later, with 300+ miles of driving and no more CEL

I'm happy!