Guess the code!

I have a 72k mile completely original 2004 Tacoma single cab 5-lug 5 speed. It has received dealer oil changes every 5000 miles or once year (mostly once a year due to low annual mileage) and 2 new air filters (every 30k miles). It still has the original front brake pads and the dealer told me in February that they have about 30% of their life left. I know it has a slight exhaust leak, for about the last 3 years. I filled it up Sunday, drove it about 1/2 miles home, and parked it until I drove it today (Tuesday). Today, while on the freeway going 65-75 mph (I use the throttle a lot more than the brakes) it threw a check engine light. Tomorrow I'll go out and see what the ODB2 reports...

In the mean time does anyone want to take a guess as to the code I'll find?

 

P0420

 

P0171

 

P0430

 

I got codes P0441 (Evaporative Emission Control System Incorrect Purge Flow), P0442 (Evaporative Emission Control System Leak Detected, Small Leak), and P0446 (vent control circuit malfunction). They are each set twice.

Since I filled until the pump shut off, drove it only about 1/2 mile, then parked it for a couple days, I wonder if I got fuel in the charcoal canister. I had an old Bug actually pissing fuel on the ground when I did on my way to work one day. You fill your tank with fuel that is roughly whatever your underground temperature is in your area, around 55F in the Seattle area.

Perhaps it's just the gas cap, it is original. I took a look at the big o-ring seal on it and that seems fine but the cap is 21 years old.

Any diagnostic tips to narrow down the problem? A gas cap is pretty cheap as a test, but if possible I like to pinpoint the problem rather than throw parts at a problem until it (hopefully) goes away. I ran some errands today and can confirm that there is no vacuum at the gas cap right after shutting the car off with a warm engine.

 

I found a video that showed a test of the purge valve. My valve fails that test, but I will try again tomorrow after a longer drive. It is off when the pickup is cold, but it's also off when the pickup is warmed up for 15 minutes and then taken out for a 2 mile drive.

 

X2

 

Nope, but thanks to all for playing. The codes are codes P0441, P0442, and P0446. Does the test of the evap system run at any fuel level? The tank is completely full right now and I only burn 5-6 tanks of gas a year (truck has 72k miles on it).

 

Did you pack the tank on the last fill up?

 

I filled to pump shut-off, no topping of the tank. I've done that many times, but I usually don't then drive just 1/2 mile and park the truck for 2 warm summer days.

 

If you have done it many times in the past, you may have saturated the EVAP.