Help! Check engine light was on for some time when I had filler neck and cap replaced. Computer sensors did not re-set until 501 mile mark, when light came on again. Checking the web, I find that some who appear to have knowledge of problem say it could be hoses, sensors, valves, or evap canister–the charcoal canister.
Mechanic who did original smoke test and recommended replacement of filler tube wants to replace evap canister without checking anything else. I feel he has dollar signs in his eyes. Another mechanic is ready to do another diagnostic, but that will cost additional money.
Question: what should I do? At wits end, and car needed to pass inspection 2 days ago.
I don’t know if you have special rules in Manhattan but here in upstate NY we can pass emissions test while having One system not ready to read. The evap system is usually the last system to reset. You need someone with a code scanner that will read i/m monitors to tell you when everything else has reset. Or , disconnect the battery a d drive it for a day and 1/2 and if the check engine light has not come on yet, get it inspected’
Something that often damages the charcoal canister is the habit of topping off the gas tank every time you fill up. When this is done on a hot day and the car isn’t driven very far, the gas in the tank expands and raw gas gets into the canister. Eventually this leads to plugging up the canister or purge valve failure.
Most of the time, you get a P0442 or P0446 first. If you don’t add gas after the first click of the handle, this will usually clear up itself with a little time.
However, since you got a P0440 code, which means it has detected a problem in the system but it hasn’t isolated the problem, then you could have something as simple as a vacuum leak in the system or a damaged or plugged hose, it may not necessarily be the canister itself.
If you have topped off in the past, I would suggest that you simply stop on the first click and wait a week or two before doing anything else. If it is just a canister clogged with raw fuel, it will clear itself in a few days, the MIL should go out within 3-5 days if driven daily. The code and ready light may take another week before ready to pass the smog test.
I have been fighting this with my 2003 Avalon. The easy thing to do is buy a Toyota gas cap and put it on after clearing the code. See if it comes back. Besides doing a smoke test to check for leaks, they can check the VSVs, which are a common source of this problem in this group of cars.
As well as the evap cannister–but that is expensive.
What you are proposing is known as “gaming the system” . . . at least where I live
A relative of mine asked if I would do exactly what you described, because his MIL was on
I said, “Bring the truck over. I’ll diagnose it and repair it. After verifying the repair, I will clear the code, let all the monitors run to completion and get it smogged legitimately”
As a Toyota professional tech, I’ve been burned a few times on the 2000 and 2001 Camrys with this code. It’s the canister. Smoke test will show no leaks. It’s frustrating. Once bitten. Experience will now condemn the canister. Even if all vsvs click. It’s that darn canister.
Take it to a reputable (read will stand behind their diagnosis) Toyota dealer. I’m guaranteeing you it’s that damn canister. Toyota master tech with over 15 years exp.
Ditto for my 2002 Sienna, Tilted Tree. It now has like 198,000 on it, and I drive it to Mexico. Several years ago I started getting the sequence intermittently, sometimes 0442, 0r 0446, maybe something else. Then, it would go out again. At one time it went months without coming back on.
This went on for more than a year. I was not going to take it to the dealer when it was so intermittent. If Tilted Tree had been there, it might have been okay. But, I worked in a high tech factory, and intermittents can burn up a lot of money that I don’t have.
On Sienna Chat, a man reported he had the same intermittent issue, but he had two identical Siennas. He swapped the canister, and the problem followed. He said it looked like there are some valves on the canister which are pressure or vacuum operated, rather than being powered, and they stick.
He bought a new canister and put it on. Problem solved.
I took my car to the Toyota dealer and requested the canister be replaced, without useless and expensive troubleshooting. They had me sign a waiver that I was taking responsibility for the diagnosis. Problem solved, and it has been several years.
A lot of problems reported here with faulty purge valves. Don’t dismiss that as a possible cause. If this were my car, I’d first do a careful visual inspection of all the evap devices and vent hoses, make sure everything is intact and in the correct place, all the clamps are there, and no leaks. And since the filler neck and cap were replaced, that area would be suspect to, and should get a good visual inspection. If all else fails, I suspect a Toyota knowledgeable mechanic with the Toyota-specific scan tool could diagnose it to the exact part, without a bunch of parts swapping.
I wonder, if it turns out to be the canister as suggested above, then is it possible to clean the existing canister instead of buying a new one? I presume replacement canisters are expensive. On my early 90’s Corolla there’s a procedure in the shop manual for cleaning the canister. Involves using pressurized air, following in a prescribed sequence, blow in one port, block other ports, let it escape from the one remaining.