check engine light for EVAP

Wow, serious shotgunning here? Or were you already replacing the plugs and O2 sensor which by the way don't affect your EVAP system.....

P0441 is for incorrect purge flow. This can be a result of different components failing, the most common being the VSV for CCV, or the VSV for pressure switching. Sometimes a faulty pressure sensor on the tank will cause this failure as well. This is not an exhaustive list, as other failures such as an intermittant leak can cause this, but that is USUALLY detected and a code p0442 or P0456 would be set.

 

Papawally1, It sounds like you have run the gamit as well. Have you solved your 0441 code? I've been told the areas around the fuel pump and fill valve in 01-04 models been know to rust and/or gasket deterioration? I firmly believ for me the issue is with gas tank components and I'm going to pull my tank down to have alook and hope I solve this fiasco. I will reply back. Very frustating, I've been dealing with these code 441/442 since May.

Bamtoy1997: I just read your comment around "faulty pressure sensor on the tank will cause this failure as well". Can you tell me more????

thank you!

 

The entire diagnostic system bases itself on this pressure sensor. When the EVAP system performs the test, it seals and applies a vacuum to the system. Then it measures if the vacuum was achieved, and if so, how much it deteriorates during the test. If the pressure sensor was bad, the wrong data would be sent to the computer, resulting in a code that was false.

 

My plan is to try an OEM gas cap and to reseal the other 2 gaskets on top of the tank. I believe the culprit is the gasket under the black plastic thing on top of the tank.
Anyone know what this is called?
Anyone know why it takes more cranking to get started after filling up?
The valves under the hood both click on 12v

 

P0441 again today
@&$)):)&&@@)(;:/--/;()$&&

 

Yes tank was rusted around black plastic thing

 

As always, it's hard to read through Bama's post without boobies distracting me. Anyway, I went through these codes with a Nissan Pathfinder and found my charcoal canister was ruptured and these things aren't cheap from Nissan. I did not replace it but was able to screen off the granules with a screen door mesh. I also found that the lines were plugged up with these granules all the way up to the purge valve in front of the vehicle. I was able to flush this out with compressed air along with water as it was completely clogged(all lines disconnected) then no more light. Well, at least for two weeks long enough to pass smog inspection which was all I needed as I won't be paying close to $300 for a new canister on a vehicle that's worth less than a $1K. Evap system is a tricky one as it can trigger other codes associated with it. Anyway, check all the lines for clogging and leaks and tighten those clamps.

 

awesome Papawally1, finding what I think has been the thorn. (for me anyway the last seven months) Are you replacing your tank or were you able to repair it? I believe I too will find the same issue with my tank once i drop it beacuse I've run out of things to replace. I will let you know, thanks for keeping the lines of commuication open on this matter.

 

I don't trust DEALERS any farther than I can (spit) into the wind, so I had a service station that I trust diagnose my 2 idiot lights that have been on for weeks, where the codes refer to evaporative emissions problems. He said it's NOT the usual pinhole in the filler neck, but without a doubt it's the vapor pressure sensor INSIDE the charcoal canister, and THAT all will cost me over $900 but he says it MAY be covered by Toyota's 80,000 mile 8 year warranty on this system. I called a DEALER who said the canister IS covered but the pressure sensor ISN'T. Can anyone confirm this?

 

I bet the gas tank is rusted through somewhere around the top side. That's where salt, dirt and moisture do their dirty deeds.

 

Been reading through the thread for clues, as I just had a P0446 pop up, but not sure how much visual inspection I will achieve before needing to have a shop pinpoint the issue.

 

2012, Tacoma, 2wd, I4, 54,000 miles.
Engine Check light and Trac Off, lights have been on for a week or so then off, then on again so I thought I would get it checked out.

I Googled it and it took me here to this thread.

I am at Jones Toyota service department (MD) right now. He just brought me the news,
"Sir, your evap canister is bad at the tune of $1,100.00+. We have to pull the bed off."
Me: WTH!!! This is BS. Blah, Blah, Blah..... I bought a Toyota to avoid this type of stuff, blah, blah, blah....!
Him: "Sir, I'll see if I can get it covered under warranty."
Me: "Thank you"

I'll continue this when he gets back.


EDIT:
He just came back. It will cover it under warranty. They are going to set up a loaner vehicle.



.

 

Home now with a 2014 Camry loaner. Truck should be ready tomorrow.
From the search sounds like the, code/lights, could be caused by one of multiple things or a combination, correct?


.

 

This blog has given me an enormous amount of information!

Same issues just recently started, with mine, and only after about 280K miles. Yeah I do a lot of driving. Put 300K and 400K on two other 1998s.

Question for anyone, when referring to the fill check valve, is that the flap that would spring closed so you cannot look down the pipe further than say four inches? Normally would be just where the nozzle would go into. I only recently noticed that I cannot see this anymore.

Next question: When you say overfilling, is it NOT over filling if you just leave the fuel pump nozzle in until the nozzle automatically shuts off the pump?

This blog has given me an enormous amount of infomation, (and also being in the controls market in the HVAC and Industrial market has helped to understand some things) Would this also be the reason I am getting both MAFS codes occasionally when kind of stepping on the throttle, even though I replaced the MAFS?

Lastly, I think I have boiled down the problem codes I get PO171 or PO174 to failing O2 sensors on each of the manifolds. Sound correct?

I have been riding around with the reader and watching everything for quite a bit. I also only first started to use some fuel cleaners, and that seemed to help, but not a real cure from what I can tell.

Thanks for anyone's help!

 

The fuel cleaners helped, for the too lean issue, but gradually the codes are coming on more frequently now, and the reader says that the O2 sensor test has failed, even though previously it would pass intermittently.

 

I think you got your money's worth out of the o2 sensor.

 

Sure...but there are three O2 sensors to replace. Anyone know answers to my previous questions?

 

Just for anyone who may still be following....I believe I have resolved everything. Keep in mind, I have an 09 TRD with 300K miles, and have been riding for many miles now with a code reader connected. This code reader has the capability to display pending codes before the go permanent (shows engine light on dash), has a readiness test to show all tests pass, fail, or incomplete for Emissions, and display live data. I had all sorts of codes flying Mass air sensor, catalysts too low in bank 1 po420, 2 po424 and final. also p440. I first replaced MAF sensor, did not work. I started using fuel system cleaner since the fuel filter is internal to th tank as a part of fuel pump assembly. This helped quite a bit especially with the catlyst bank 2. I changed my PCV Valve helped even more. I replaced the gas cap, and I believe this also helped for passing the EVAP test. I started to realize that all of these issues seemed to be a part of combustion air flow drop, yet I change my air filters every time I change my oil. BUT, BIG BUT, on at least the TRD types, the breather has a flow straightner (or final filter, I think a straightner because I am a controls guy for my career) after the disposable air filter itself. It was frustrating that this filter/straightner doesn't seem to be able to be removed, so I sprayed it with some carb cleaner. Amazing results, but still occasional Air flow code, and PO420 catalyst too low bank 1. I took the breather off, and almost emptied a can of Carb cleaner on both the exposed side and into the opening where it attaches to air valve. even shook the fluid around by shaking the breather body. NO MORE MAF code even as a pending code. Keep in mind that before a code hits your dash, it will be in pending code for a while both time, cycle, and miles. Plus it is the yests that make you pass the emissions test. In fact, I have a green light for passing all the tests including O2 sensors and EVAP test complete, yet the catalyst too low was still throwing a code. Also, the EVAP test takes a considerable amount of miles, time and on/off cycles to complete. I would only erase codes once the went from pending to stored, since every time you erase codes, all the tests reset, and the EVAP one takes a long time. Well the bottom line here is that with restricted combustion air flow, anything that uses vacuum (EVAP) will give you a problem if your Combustion air is restricted since it is this air that creates the vacuum. Also, if starving for air, any other O2 sensor or catalysts codes can be affected. The only code I get now (and sometimes resets itself to okay before going to a stored code) is PO420 Catalyst too low bank one. Well the only way any of these Catalyst codes are developed are from the O2 sensors. one on each ex manifold and after the Catalytic converter. I have the new O2 sensors, waiting for the weather to be okay for the replacement, since I can see that my bank one sensor's value when reading live occasionally goes negative. I hope this helps anyone else. it just goes to show you that sometimes its not just replacing parts, and you have to look at the entire system. For instance, you could also have a bad spark plug cause an O2 sensor code. Anyway still going strong with engine running like new, as well as fuel economy at 301,858 miles. Oh, and the guy that said the metal flapper on fuel tank neck is important to the EVAP system is wrong. just look at the little hole tap that is above the flapper which is where the EVAP is pulling the evaporation of gas fumes from, and the flapper would need some sort of seal to make it bubble tight. The flapper is a check valve/backflow preventor safety so if you leave your gas cap off, and start driving the gas wont fly out. But I agree, over filling your tank could do damage to your EVAP system, which I never do anyway, since you can now have liquid gas get sucked into the evap system rather than just fumes. I am concerned about this now since my flapper check valve is missing. Good Luck. I know I'll pass my inspection coming in March at 300K +!!!

 

This link has some great advice to clear up many of these problems.:

http://www.tacomaworld.com/forum/pe...ary-air-filter-diy-another-way-1gr-fe-v6.html

 

My check engine light just went on this morning. I went to Oreilly. The code refers to a bad Charcoal canister, emissions system, gas cap, vent valve solenoid, or purge valve solenoid, however I didn't ask the technician what the specific code was. He suggested I make sure my gas cap was tight. Interestingly, when I opened my gas lid, sure enough the gas cap was loose. I tightened it and then filled up the truck. The check engine light is still on.

There was a lot of helpful tips suggested in this thread. Does anyone have a suggestion based on all of the above information?

Thanks for your time. Rock on!