CEL - Multiple Codes

So I’ve got a 03 Taco with the 2.7L motor.

Recently, I had to have my fuel tank replaced, and had the fuel pump replaced too due to rust. My old tank had a hole that was leaking fuel.

Recently, I’ve been getting a P0441, P0442, and P0446 codes. After some reading, I decided to start small. Replaced the gas cap. The light came back on. One thing I did notice is there is NO HISSING when I loosen the cap.

I just ordered the Vacuum Control Valve. Waiting to replace that.

No drivability issues I’ve noticed. From what I’ve noticed, the emissions hoses seem to be in good shape.

What am I missing?

 

I beleive there is a vapor pressure sensor that is either malfunctioning or there is actual vapor leakage. While it is possible for a driveway tech to figure it out eventually, it is easier to get someone with experience to smoke test the system if needed. One thing you could do is in the engine compartment look for the evap line that has the green cap on it and make sure that that cap is on.

 

I chased a small evap leak for about 3 years. I smoked the engine and found 2 in about 5 minutes. $20 well spent.

 

I’m might end up doing a smoke test with my local mechanic if this VCV doesn’t do the trick. It’s been about 50+ miles and the light has t come back on yet and that is BEFORE I replaced the VCV.

 

The evap system monitors are a 2 trip test. The engine has to be be cold and the intake air temp sensor has to be withing 10 degrees of the engine coolant temp sensor and the engine has to have been shut off for greater than 8 hours and the fuel tank has to be between 1/4 and 3/4 full otherwise the monitor will not run and like I sad at first, this has to happen twice. Mileage driven has no bearing on this test. If this is a smoging issue some states, depending on M.Y. of the vehicle, allow for one monitor, usually the evap monitor to remain incomplete and still have the vehicle pass smog.

 

So I replaced the VCV. It was really difficult since it was in a tight spot. I cleared the light before replacing the VCV at 84,931 miles, and after replacing the valve, I’m at 85,015 and more than a half a tank, and no light.

Hopefully that did the trick. I have noticed no hiss sound when undoing the gas cap.

Today is in the 80s and I have more than a half tank left.

 

P0401 comes and goes on mine. Triggers the CEL every once in a while and goes away on its own. I replaced at least 2 valves, EGR valve and checked for leaks on the engine bay, still does it to this day I also replaced the filler kneck and nothing.

Been trying to get under the truck and take apart some components of the charcoal canister to see if they're stuck but haven't gotten to it.

 

Ended up taking it to my mechanic. He charged $59.95 for the smoke test and found the leak. There is a hose, right above the fuel tank that connects into the canister that was pouring out smoke. An old hose that had dry rotted and split. It’s been replaced and light is off!

 

I never thought about a Halloween fog Machine as a diagnostic device until that damn evap leak.