Camry recurring CEL issues

I have a 2000 Toyota Camry with 90,300 miles. Last week check engine light came on and mechanic said it was P0440 and charcoal canister needed replacement. Did the repairs and 20 miles and two days later CEL is on again. Take it back to mechanic and codes this time are P0441 and P0446. I’m told I need a new gas cap, so it’s replaced with new one from dealer. 15 miles later, CEL comes back on and I return to mechanic. This time it’s reading all three codes, but they can’t find anything wrong. The only parts not replaced are the vacuum seal valves, which mechanic says test as good. They reset lights and 15 miles later, the check engine light is back on. My mechanic is baffled. Any ideas about what the problem could be or what they should check? Car drives fine, but light coming on is annoying.

This is how to diagnose the problem if a Toyota comes up with any of these codes.


Me thinks you need another mechanic. You have a leak in the purge control system or the vent valve isn’t working.

Normally I give the lecture on not overfilling your gas tank, but since the canister was replaced, if this was the root cause, the light should not have come back on. I think you may actually need the vent valve or purge valve replaced, but it is remotely possible that an electrical connector or vacuum line came loose or was not reconnected after the canister was replaced.

Thanks for the tips. I’m going to take to the dealer instead of my regular mechanic and now I’ll have a better idea what to talk with them about.

Give your regular mechanic at least one more chance to check all connections and lines in this system. Something could have come loose or he could have got a couple lines crossed. If he finds a mistake, he can fixit at no cost to you.

BTW, if you are in the habit of clicking the nozzle several times after it stops at the gas station, then this is why you are having this problem now. You must stop on the first click.

Another urban myth.

Since OBDII was mandated, it’s impossible to overfill the gas tank to the point of saturating the carbon canister.

The EVAP system has rollover/over-fueling valve at the top of the gas tank. This prevents gasoline from running out of the top of the tank into the carbon canister and out the vent valve in the event of a rollover. This valve also shuts gas off to the carbon canister if the gas tank is overfilled.

The EPA knew some people would try to stuff the gas tank. So this valve was installed to prevent damage to the carbon canister for that reason.



Check this out. This has your name all over it

Here’s what the part looks like, if you happen to have the 5S-FE engine

Good luck, and please let us know what happens

As old as the car is doubt th e TSB will work. Evan codes are simple with the right equipment, the Toyota factory scanner has all the data and self tests for the evap system. Most independents don’t invest in the tools to do proper evap system diagnosis due to the costs. Look around for a well reviewed local dealer. Evap codes are one of the most common I see from independents followed by airbag concerns.


Why do you doubt the TSB will work?

Because you don’t think it’s that part mentioned in the TSB?

Or because you think a small independent shop might not have a scan tool capable of running the tests mentioned?

My snap on scanner does reasonably well for Toyota, and it’s a fairly common tool. I don’t have a 2000 camry to hook up to at the moment, but I think it could do those tests

In any case, that part is fairly cheap, and I think it’s worth just replacing it, letting all the monitors run to completion, then recheck what passe, and what didn’t

I bought my own otc smoke machine, because the shop’s machine broke, and it’s clear it won’t get repaired. It’s actually one of the most used tools . . . by me

If you do enough evap diagnosis and repairs, and have access to some decent service information, it’s not always a nightmare. But if you don’t have a halfway decent scanner, have no smoke machine, no access to good information, it could be a real challenge, to say the least

Of course, intermittent evap problems are no fun, even if you have the tools and information

A few months ago, I was working on a Ford. the darn car had the check gas gap illuminated, but not the mil! There were no stored codes. In any case, I had to look at mode 6 data, to see what had actually failed. Then I had to convert that raw data into numbers that meant something to me. And I had to go to a ford website to read a description of how the evap system monitors itself and in what order it tests itself. It took a few hours of reading and staring at the scanner screen, before I even started making headway

Usually the bulletin parts fail early on the TSB is from 03. You have the knowledge and tools to diagnose problems like this. Many shops don’t, it’s sad the number of people in this industry that are simply parts replacers and wallet flushers.

This comments below are not made in defense of parts replacers and wallet flushers but there’s a point to be made.

Many people do not like to spend any money on their car; a tool they use every day.
Many people think that any charge no matter how fair is an overcharge and they’re being ripped.

So if someone brings their car in to sort out an electrical problem how many will authorize an open estimate to find that problem; no matter if it’s an hour, 10 hours, or a week?

If someone has an issue that requires a battery of tests how many will authorize a shop to perform Test A at X flat rate hours, Test B at X flat rate hours, Test C at X flat rate hours, and so on and so on…

Many feel that if a shop bills .8 of an hour for a diagnosis and an hour for the actual repair they’re being taken advantage of and think an hour should be all inclusive.

Tester, there is a rollover valve in the vent, but I can’t see how it prevents fuel from entering the vent line when the tank is upright. It closes when the tank is inverted. and it does not float.


You bring up a good point, about faulty parts failing early

I didn’t really look at the date of the TSB

Tester, there is a rollover valve in the vent, but I can’t see how it prevents fuel from entering the vent line when the tank is upright. It closes when the tank is inverted. and it does not float.

Floating or not, what stops you from adding fuel on top of it all the way to the brim?
I believe it is a roll-over valve only. It’s job is to stop fuel spills from contaminating the environment in the event of a roll over. It does nothing to stop someone from continuing to fill the inlet all the way to the top, past the vent line connection.

It’s a ball with a weight below it.

When the tank is being overfilled, the ball floats up and blocks the hose to the carbon canister.

If the vehicle rolls over, the weight pushes down on the ball and blocks the hose to the carbon canister.


Hmmm, I went and looked closer based on Tester’s last post. The gas cap is a vapor tight closure so the main line doesn’t need a valve per se to stop fuel from leaking out. The vent line has a roll over valve to prevent liquid gas from escaping out that way in the event of a roll over. Here is a description of one:

“ROLL-OVER VALVE is sometimes used in the vent line from the fuel tank. It keeps liquid fuel from entering the vent line after an accident where the vehicle rolled upside down. The valve contains a metal ball or plunger valve that blocks the vent line when the valve is turned over.”

I couldn’t find any descriptions that included a means for it to close upon liquid fill level…hopefully someone can find one…I can see how that would be a good enhancement.

I too have a 2000 camry I too have had this cel code on my car I replaced the vsv by the gas tank this solved my problem you can buy this part from the dealer for fifty dollars