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Evap Purge Valve

by alex r June 14, 2010

I have a 1998 toyota corolla and the check engine light is on. The code came back as evap purge valve. I would like to fix it myself but I'm not sure what to do. Do I just need to replace the evap purge valve. Please Help!

For most EVAP related codes, the purge valve is the most common culprit. Do you have the exact code that was thrown? As with any OBD system, cannot just blindly go by the code - as there could be a related system that is causing the code to the thrown. If it is the purge valve - it would be on the vapor canister, underneath the car. Valve itself is not expensive - usually runs about $70-$75 - but getting to it and replacing it can take some work. If you haven't already tried - reset the CEL and see if the code keeps coming back. More than 1/2 the time - the code will never come back - essentially the ECM cried "wolf" for EVAP related codes.

I just spent $160 replacing the evap purge valve and the gas cap and I reset the light and it came right back back on. I just want to get the darn thing inspected. I'm so frustrated. What do I do now?

Did you diagnose a bad purge valve or just went on the OBD-II code that was thrown? What is the code or codes that are being set? Like I mentioned above - cannot just go by the OBD-II code - as a completely unrelated system could be the root cause of the initial CEL.

Its codes PO441 and PO446. I put a charcoal canister on it yesterday and I reset the CEL. I then drove it for 50 miles and was able to get it inspected. Hopefully it is fixed for good! Thank you very much for taking the time to give me advice. For future reference do you know how I can test one of those evap purge valves? Is it just a solenoid I can hook 12 volts to and listen for a click? Oh and by the way when I went to O'Reillys to get a new gas cap they sold me the wrong one but when I went to the Toyota place to get the other parts he looked at my old gas cap and told me it was ok.

Oh yeah I meant to tell you my purge valve is on the back of the air box. Very easy to get to but expensive. Charcoal canister was $300

Yeah, the P0441 and P0446 are pretty common on the 8th gens that seem to have the EVAP issues. Either you get EVAP codes or stuck piston rings - in my car, I get EVAP codes and CEL seemingly every other year, about a week or two before I need to get my car smogged.

As for being "permanently fixed" - hard to say. If you drive a few hundred miles and the CEL stays off - then I'd say you got the problem licked for now.

For some diagnostic testing - just follow the link in my sig (Photobucket account) - under the EVAP system album, there are some screen caps of the diagnostic procedure and location of the main EVAP system parts.

My car also got the P0441 and P0446 combination CEL - but it turned out to be a bad cut-off valve at the top of the gas tank. Almost every shop I took the car to said that all the VSV valves and vapor canister needed to be changed. I took it to the dealership to have it leak tested - using an EVAP sniffer, the tech pinpointed the leak to the cut-off valve. $30 part + $360 in labor. I opted to buy the part and change it myself. At the time, I also noticed a potential leak on the gas fill tube vent line, but didn't address it when I changed the cut-off valve. All my current CELs are likely being triggered by a leaking vent tube.

  • 149 posts

Don't overfill your gas tank trying to "round up" to the next $. When the pumphandle shuts off, hang it up.

Overfilling the gas tank will damage the evap cannister too.

Yeah your about the tenth person to tell me not to overfill. I have been guilty of that

I have a 2007 Corolla, Check Engine lamp is on ,Code's P043E,P043F,P2401,P2402,P2419. Purge Valve? Car run's fine. Help!

With those particular set of codes, especially if they all come up at the same time - this sounds like the EVAP tube has water or some other debris stuck in there. This is especially common on many Scion cars.

On the earlier cars, like my Corolla - the EVAP system was placed in such a way where overfilling the tank (topping off) could cause raw fuel to enter the EVAP tube and clog the vent. They "fixed" this with the 9th gen - moving the EVAP as they had more vertical room with the beam type rear suspension. Problem with this setup - is that the outside seal could get damaged and suck water into the vent. This water intrusion can cause those exact codes to pop up.

You only need the vapor canister pump and VSV valve - unfortunately, those are part of the vapor canister, which means you'll have to get the whole assembly. These EVAP related issues generally don't hurt the performance aspect of the car at all - all they do is prevent gasoline vapors from the tank and fuel system escaping into the atmosphere.

Might try resetting the CEL, hopefully the internal pump was not shorted out by water, possible it could dry out and the codes will not reappear. Otherwise, you could be out a fair amount of money. I've seen quotes from others with the exact same codes go from $500-$800+. Some were covered under warranty, some under extended warranty, some were not covered at all.

Before you go all out - would be very helpful to get the EVAP system "smoke" checked. They inject a tracer material into the system, then use a wand to pinpoint any leaks in the system. The test can take a couple of hours - and usually runs the standard diagnostic charge. I used this to determine what part was bad and replace it myself. My cutoff valve leaked on my Corolla - a $30 part that needed over $600 in labor to get to. I ended up just getting the part, and doing the work myself over a weekend.

  • 23 posts

Useful thread! I have a high mileage 2007 Corolla 5 speed, bought in 2008 with 46K, now at nearly 292K. We recently made a rare visit to the dealership, had their "120K service," because my wife could hear the belt a bit and I figured it had been over 100K since plugs, belt, air cleaner, etc. This car is a rural highway commuter.

Shortly after we got the car back, we saw the CEL. Code reader said "10 codes," but it turned out to be five, then the same five with the "pending" symbol. P043E, P043F, P2401, P2402, P2419. The reset but returned. Once, I also saw P2451.

We've now established a pattern. Head to work in the morning, and see the CEL. Plug in the code reader and reset. Car sits for 8½ to 10½ hours at work, then heads home, no CEL. Fire up next morning, and there is the CEL.

The only other thing we've observed is that a few times we've thought we had the fuel tank 100% full, but it was not. Maybe there's a partial restriction there.

We have a bad habit of filling as much as possible. I see here that it's a bad habit. We'll have to do something else to establish consistency in filling so we can track fuel mileage. BTW, real gas gets better mileage than gasohol, as you'd expect, and winter mileage seems to be worse. We buy real gas when we can, but that's probably less than half of the time. Premium seems to yield better mileage, so that implies less alchohol in premium. I need to buy a kit from and find out.

Given that we have high mileage and we've done very little to the car (clutch and front brakes around a quarter million miles), should I first locate that EVAP tube and try to clear it, then maybe order a new vapor canister? I think that's a $200 part.


Depending on where you live at - sometimes premium fuel has as much if not more alcohol in it compared to the other grades - as alcohol is an easy way to pump up the octane rating.

The higher MPG you are seeing with premium is likely due to the high octane preventing the timing from being pulled as much from detonation. With that many miles on the car, you likely have lots of carbon build-up in the combustion chambers. With regular gas, you can have detonation that will cause timing to be pulled, more gas to be dumped in to help cool the combustion chamber - engien still runs well, but eats more gas. With higher octane - you won't get this as often, depending on the severity of the detonation - your MPG may actually be much higher with premium fuel.

My 2002 Corolla acts the same way - with premium, not unusual to see 10-15% better MPG running just premium. Depending on the cost difference between the grades - I could actually save money running premium fuel.

As for the codes - unusual to have that many on this particular generation of car - more telling is that particular group of CEL codes.

P043E, P043F, P2401, P2402, P2419

If you look these up online, you'll note that a large number of owners have this particular group constantly pop up on them - crosses into other Toyota models as well (Lexus and Scion). Most are traced down to a clogged vapor canister - can be due to overfiling the tank (fuel will wick into the vapor cansiter) or from water intrusion (cracked case or cracked EVAP tubes sucking in water). In either case - the fluid in the canister will cause the VSV valves to get stuck / electronics to short out - causing those codes.

On a small number of units - especially if you get additional fault lights come on (TRAC OFF / VSC / CEL) - this may point to a faulty ECM, rather than an issue with the EVAP system. This was especially common on vehicles that had a lot of ground clearance (no change water would get to the canister) and the vehicle is not overfilled. This is what happend to my Rav4 - luckily, I found out of about it before they wanted to change everything the EVAP system touched (valves, canister, tank, vents, fill tube, etc.).

With the ones with a truely clogged vapor canister - the real issue is that replacing the vapor canister will only temporarily "fix" this until the canister get plugged again. For some owners - they've been down this road 3 or 4 times - because the real culprit wasn't addressed (overfilling, cracked EVAP hoses, environmental issues, etc.).

Fortunately, you've already sort of diagnosed this as a plugged vapor canister - as you've gotten the CEL to pop on after a cold soak and after initial EVAP I/M readiness monitors were set. That's why it won't pop the CEL after you reset it and let it cold soak - some of the I/M monitors didn't set. After you drove enough to set a monitor, the following cold soak will pop the CEL. If it was an ECM issue - those code will be popping up a random times.

My suggestion is to get the whole EVAP system smoke checked - that way, they can pinpoint which valve is defective and if there are any leaks in the system. Once they've identified the trouble points - if you are DIY inclined, you can opt to tackle those defective components yourself and save on the labor charges.

  • 23 posts

Thanks. It sounds like I'll be taking another pocket full of money to the dealership, though as you say, if I can find time to swap the parts I can save a lot on labor. Funny it popped up right after they'd worked on it, but could be coincidence. We'll definitely make an effort not to overfill.

You've given me something to think about regarding fuel. My brain lives in the past. I recall 1980's turbocharged cars with knock sensors to limit boost, but wasn't thinking about a detonation sensor in the engine management system of my economy car (then again, once upon a time variable valve timing was considered extremely exotic) and a system that constantly adjusts timing according to a lot more input than just rpm and throttle position.

Hmm... carbon buildup.... I guess the old trick of pouring a glass of water slowly through the carburetor is out. default_smile Are there any fuel additives on the "snake oil shelf" at the parts house that will actually remove carbon buildup? I know premium fuel always claims to do that.

Overall, this car has run a lot of miles and we've done amazingly little to it. I know it will get tired someday. Maybe I'll find another one then.

Interestingly - that water trick will still work. Instread of dribbling it down the carb's throat - you let it get sucked up by a vacuum source (brake booster is one possible source). Lots of people use Seafoam to clean the upper end of the engine - though I've seen more mixed results. Some definitely benefitted from the cleaning, but quite a few have noticed that the new found cleanliness is short lived. After a few weeks, you are back to where you were before, all the carbon came back. Has a certain entertainment value - the amount of smoke generated from the "steam cleaning process" can be comically humongous. Definitely do this outside of crowded neighborhoods.

Also have to watch the amount, as you could hydrolaock these engines. The 1ZZ-FE is an interference design with timing chain - definitely not going to be cheap to work on if something goes sideways.

As for additives - anything with PEA as the working ingredient will work. Developed by Chevron more than 30 years ago, still showing good results even in today's cars.

My #1 go-to is Redline Sl-1 Fuel System Cleaner has the highest amount of PEA in it (~50% by volume) - one bottle will treat up to 100 gallons of gas. Used full strength (one bottle with full tank fo gas) for heavily neglected engines. Works like magic on my older muscle cars - those get fouled in a heartbeat.

Can be hard to find - so my other go-to ones are Gumout w/Regane. The High-Mileage Fuel System Cleaner variant has the highest amount of PEA in the Gumout line. Techron Fuel System Concentrate is next, just make sure it is not the cheaper Fuel Injector cleaner variant - as it has almost zero PEA.

Some reported good results with MMO (Marvel Mystery Oil) - couple of ounces in the gas tank. Same with Lucas. Though, I've never seen anything happen with those in the car, might just be an issue with getting the right concentration in there.

Some prefer to attach the carbon directly - in that case, 3M makes a unique kit that plumbs into the fuel rail and you literally run the engine on this special solvent. Involves a pressurized solvent and special manifold to shoot the solvent through the fuel rail, through the injectors, and into the combustion chamber. Getting it connected would be the trickest part - Toyota uses a returnless fuel system, so there isn't an available schrader valve or inline-t anywhere like they used to. This would involve getting a SST (Special Service Tool) to disconnect the fuel line running to the fuel rail, disable the fuel pump, and use another SST to add in a T. Total pain.

Hi all,

We have 2 Corollas, a 2003 Corolla S model (and a 1999 with over $300k miles on it). Last Sunday my husband took the 2003 Corolla to the car wash and because it's been so snowy here the car was full of salt, he had them wash the undercarriage. Later on that day I started the car and the CEL light went on. I drove over to Advanced Auto and they checked the code and came back with P0446. So I looked it up on line & saw the service bulletin that says it can be either the gas cap or the fuel filler tube. So I bought a gas cap (cheap one) and disconnected the negative battery terminal to clear the light. I drove for the next week and thought everything was fine & that was the end of the CEL. Then yesterday it came back on. My next step is I have ordered an OEM gas cap. If that doesn't work, I guess I'll have to go get it diagnosed. I still think it's odd that right after having the undercarriage washed, the CEL came on.

Any ideas, thoughts, help of any kind, would be greatly appreciated. Even though we're from the Motorcity, we're both prertty useless when it comes to cars (I did change the headlight bulb once). The new gas cap is supposed to be here tomorrow. Do you think this time we should see if the light goes out on its own instead of disconnected the neg battery terminal?

It might just be coincidence that the MIL was set right after getting the car through a chassis wash - but weird stuff has happened to owners.

Really should reset these MILs with a scantool. Pulling power will work, but generally have to leave the power off enough / drain down the backup battery in the ECM to completely clear it - or it could get the ECM into a funky state / repeat the last trouble code. I would disconnect the power for atleast 10 minutes and make sure to step on the brake pedal / turn on the headlights to help bleed that backup battery down completely. Note that all the learned parameters on the ECM will be lost and your readiness monitors will all be set to "not ready" - the drive parameters will be reset pretty quickly, but the readiness monitors (the ones that emissions shops look at) will take some time to set. Could be a couple of days to weeks, depending on how you drive.

As for the gas cap - pretty common for the rubber seal to dry rot - as gasoline fumes are contantly trying to eat it. Definitely get the OEM cap - well worth the couple bucks difference in cost. On my 8th gen - used a Stant cap, as they had a bunch at the autoparts store at the time - never sealed quite right, always got EVAP codes (P044x). Got an OEM cap - problems went away. If you compare them side-by-side - there is a marked difference between the aftermarket and OEM design.

Uncarriage wash knocking something loose? It is possible - depends on how strong the spray was and how long it was directed at the EVAP system. Pressure washing the bottom of the car generally isn't strong enough to damage anything, unless something was bad to begin with and they were purposely training the pressure washer's wand right at the EVAP canister and the associates tubing. If it was one of those spray bars that you run over with the car to wash the bottom (automatic carwash), then no way is that strong enough to get water up there.

The 8th gen (years 1998-2002) one is closer to the ground, so that would be more likely to get damaged, if the spray was strong enough. On the 9th gens (years 2003-2008), they moved the EVAP systems around - put it a little higher, so they were not as sensitive as the earlier generation for getting flooded with gasoline (ie, pumping past the autoshut off on the gas pump).

Can't hurt to jack up the rear end of the car and take a peek for obvious damage to the EVAP system. Loose vacuum tubes, connectors that got disconnected, cracked or other obvious physical damage to it.

If you don't notice anything obviously amiss visually, my gut feeling is that water got into the freah air vent or cutoff valve on the top of the tank - as soon as that dries out, likely the code will not come back. I'd put the new gas cap on the car, reset the code, drive and see if it the code comes back. If it comes back immediately, could be due to water there - drive for a couple more days to make sure the water is given enough time to dry out - reset, and see if comes back immediately. If it does - then you can spend the time to have a shop properly test the EVAP system. A "smoke" test is usually done, they should be able to pinpoint exactly where the problem is in a couple of hours with that test. Then you can decide how to address it from then.

As for drivability - these EVAP codes have zero influence on drivability - it is purely an evaporative emissions issue. Car will drive just fine with these codes set on these cars - but if you live in an area that smogs cars, then it will be an automatic failure to have any DTC set, let alone an EVAP code.

Thank you very much for your reply. You really know your stuf! I got the new OEM cap yesterday and I'm about to change it out. If I understand you correctly, it's better to just clear it out with scantool rather than disconnecting the battery terminal. I would be too afraid I hadn't drained the backup battery for ECM enough and would just mess it up even more.

I definitely like how the 2003 sits up higher than our 1999. Although when I hit a deer, I was glad the 1999 was sitting so low. It actually scooped up the deer when I hit it and then the deer flew over the car and landed to his death. Only damage to the car was the hood was totalled.

I appreciate the information about the car wash. It was just an auto wash where you drive over it to clean the undercarriage. It's been a couple weeks now so you would think it has dried out by now, hopefully.

Fortunately they don't smog test here. I just hate seeing the light on, especially after dealing with a defective clock for the last few years. Known issue with 2003 Corollas. I found some info on it on line and soddered a couple chips on the clock's board. Seemed to fix it for a year, and now it comes on and off again. Maybe this summer I'll check the sodder again, I don't have a lot of experience with sodder so maybe it needs to be redone.

Anyway, off to fill up my tank and see if Advanced Auto will clear the light. This OEM cap looks better than the cheap Stant one I had got so I'm hoping the new cap will fix it. I think I may just buy one of those scantools to have around anyway.

Just an update. Put the OEM gas cap on. Then none of the auto places would reset the MIL, so I bought a scanner of my own. I got one that plugs into the OBD2 port in the car and then you use bluetooth with your cellphone and install an app. I had no idea what I was doing, but I was having a lot of fun with my new toy. It did pull the same code, P0446. Then I cleared it. It's only been 5 days so I"m really hoping the light doesn't come back on.

Thanks again for your help, I really appreciate it.

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