P0441 and P0446 Codes

Looking for some help here on what could be going on.

A while back I started to get some P0171 too lean codes on my 2000 Tundra. The vacuum line from the EVAP valve to the VSV was dry rotted to the point where it basically wasn’t even connected. Replaced the lines along with a few others and the P0171 codes disappeared.

Maybe a day later, I started to get P0441 EVAP incorrect purge flow and P0446 EVAP vent control circuit codes. I know everyone says to replace the gas cap for these issues, but any time I remove the gas cap or the lines on the EVAP valve, there is plenty of pressure released. Correct me if I’m wrong, but I wouldn’t think it’s the gas cap if I have pressure in the gas tank right?

With this thought process, I went ahead and bought two EVAP valves off EBAY and swapped them out. In less than a minute, the codes cleared themselves. Ran without issue for 4 days, so problem solved right?

Nope - P0441 and P0446 popped back up! Any ideas on what to swap out next? VSV sensor, gas cap, charcoal canister? Like I said earlier, there’s pressure in the gas tank so I don’t think it’s a leaking gas cap!

 

You said you bought two valves. Did you try both of them? Same result with both?

fleaBay and scAmazon are terrible places to buy engine/auto parts. There's so many shit-tastic quality and knockoff/counterfeit parts that can do more damage than good, really can't trust anything that comes off there. It's the only reason I ask.

Olathe has about the best diagrams to show EVAP function of any. Vent valve and/or its wiring/circuit are one potential issue. The canister itself, I'f be surprised if it was at fault.

https://parts.olathetoyota.com/p0441-code-toyota

https://parts.olathetoyota.com/p0446-code-toyota

If the other valve doesn't solve it, I would smoke test to see if you're leaking anywhere obvious, in case that's your issue. I'd have expected to see P0442 accompanying that if it were the case. And your truck is old enough the cracked filler neck TSB doesn't apply.

 

Make absolutely sure you have all your hoses hooked to the proper places.
There is a diagram on the hood or here is a vague picture I have if it helps.

 

I want to say I had these codes a while back on my 3.4L and I replaced the gas cap hoping it would fix it, but that didn't work. I believe my mechanic ended up replacing one of the hosees and it fixed the issue. I can't remember if it was the exact codes that you had, but I think they were because they sound familiar.

 

Sorry, I should have clarified. I replaced the purge valve that’s near the intake and the sensor valve on top of the EVAP. Codes initially cleared on their own, but ended up coming back.

Just took a look again yesterday and the P0171 error came back with the P0441 and P0446. Took a closer look at the hoses on the EVAP and found one of the 3 inch hoses had a small crack underneath. Swapped that one out, cleared the codes and drove 20 miles without issue.

If they come back again, I’ll do a smoke test first to see if there’s another leak somewhere.

 

If I were you I'd replace all of your EVAP hoses, honestly. At minimum, trim the last 1/2 or so off and re-seat, then zip-tie them on tight if you don't have the budget to replace.

 

Good idea. 24 year old vacuum hoses are probably due for replacement, especially in Texas heat!

Not sure how standard it is, but I thought it was strange that there were a few specialty hoses that transitioned from like 3/16” to 3/8”…