Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2001 Toyota Corolla LE: Fuel Vapor Canister & Air sensor check engine light codes/oil low

Bought used at 110k 3 years ago, now 160k. Long term San Francisco mechanic and helpers don’t speak the most understandable English but charge low rates. Brought in to check codes etc. They said engine only had half quart of oil left!? (4.8k after last change). None of the oil change shops before had said anything about low oil so this seems out of the blue. Had heard something like radiator fan hitting something the last 4-5 days. For last 2 months had heard loose exhaust type noise I thought, apparently loose heat shield. Car sat idle all of September, since then one trip to Crater lake the only big trip besides some up and down the peninsula and daily cross-town.

Engine check light codes on bill read “P0440, P0441, P0442 EVAP Small leak” and “P0171 lean mixture” (last two fill-ups I topped off tank too much and ran a bit of fuel down the side, say 100 ml ~ 1/4 cup). After resetting it seems both canister and air sensor codes came back within days (he did not say which codes came back but I infer at least one from canister and at least one from air sensor). Mechanic said something about canister problem might be causing the air sensor code. Said canister should be replaced by Feb so system could equilibrate and smog check would work in August. I think mechanic is now saying air sensor has to be changed also…I guess because canister code did not come up by itself?

Check Engine light came back on next day.

So my questions are:

  1. Do I have to get new vapor canister (~$600, could it just evaporate back to ok status? By Spring? I think mechanic said stuff inside has melted due to topping off spill)?

  2. Do I have to change out air sensor?

  3. What’s with the sudden loss of oil and is it connected to anything else? Have not noticed any oil on ground.

  4. What questions should I ask to get clearer answer?

Take the vehicle to a professional shop to diagnose the evaporative emission control system leak, it should take 30 to 45 minutes. A leaking charcoal canister sounds unlikely. Typical failures are a leaking fuel tank overfill control valve, leaking fuel cap or leaking vapor hoses.

The lean operation code can be diagnosed at the same time, likely due to a dirty mass air flow sensor.

Was your discount mechanic able to identify the person responsible for maintaining the proper oil level in the engine? The need to add a quart of oil every 1500 miles is not unheard of, running out of oil will ruin the engine.

+1 to Nevada. Ref your question #3, there was not a sudden loss of oil. At almost 5 k miles you should have checked the oil 3 or 4 times and would have spotted a drop in the oil. It was probably being burned off slowly and could have been caught much earlier.

+2 to Nevada’s post… and +1 to Steve’s.

Nevada & Steve that person is me, 2 previous cars the oil changers told me of low amount during change so was able to monitor and add oil when necessary as engines gradually burned more oil, this was big surprise, assumed I would hear when it was not full during oil change. Suddenly half quart wth! I always ask if oil is low when changing. My mechanic did one of the latest oil changes and no word so…very unexpected…manual said 7.5k between changes…

I’ll take the car somewhere else, The Toy Shop is close…

wait a minute, shouldn’t an oil light lamp have come on? or would that be subsumed into the check engine light as an alert for everything?

Your method of monitoring the oil level seems different than what the owners manual shows.
The engine in my car consumes oil so I check the level every other month and add as necessary. It has never gone below the “add” line, if it had I would check it more often.

Your car does not have a low oil level warning light.

Not sure if I understand the OP but I would not expect the person changing the oil to know how much oil drained out unless it was severely low. Most of the time they can’t see it the container.

The engine oil can get pretty low before the oil light turns on. And when it first starts to turn on, it usually does only at idle, not when driving down the road, so its possible to not notice it. That light on most cars indicates low oil pressure, not low oil volume. The pressure can be ok and the light stays off even if the oil level is low, but low oil level over any length of time severely stresses the oil, and can quickly damage its lubricating qualities, and cause engine overheating. Depending on the sources of the noises you report, you may or may not have gotten away with it this time, but going forward its a good idea to check the dipstick once in a while. As long as the engine isn’t known to be loosing oil. I check my own Corolla’s oil every 500- 1000 miles provided there’s no signs of new leaks on the driveway. The oil light isn’t directly related to the check engine light. The CEL is primarily for indicating emissions problems.

Addressing the lean/O2 sensor code, I think that should be deferred until the EVAP system problem is fixed. B/c fixing the EVAP problem might fix the lean code too. The car’s EVAP system is designed to prevent fuel vapor from escaping into the air – a pollutant, its part of the federal emissions standards required on all cars – so the entire fuel system is supposed to be air tight. As gasoline is used, air must be admitted into the gas tank to replace the gasoline used from the tank, but not the other way. Fuel vapors in the air above the gas in the tank are also routed to the canister and stored there, until a convenient time to burn them off in the engine occurs, at which time they are purged into the engine via the purge valve. So you’ve got some problem or another with all that. Could be split hoses, bad canister, purge valve, or even just the gas cap. Or the canister could be shot. It doesn’t “melt” (as your mechanic said) so much as the carbon gets saturated with liquid gasoline.

You mention you overfilled the gas tank. Suggest you avoid that going forward, at it can damage the EVAP system. Everyone likes to save some time by reducing the number of times to stop for refilling, but the amount of time you save by overfilling your tank can prove to be time billed to you at a very high rate, once you get a mechanic’s estimate for repairing the EVAP system.

So find a shop you trust that will focus on getting the EVAP system in good order. Once that is done, if the lean code continues, they can use their scan tool in mode 6 (real time mode) to check for fuel trim, which will give them an indication what’s causing the lean condition. Make sure whatever shop you choose has the capability to check your car’s fuel trim.

If your Toyota is like mine, the owners manual tells you to check the oil once a month. If your engine was really down to 1/2 quart you will be shopping soon.

Toyota 4 bangers are well known for using a lot of engine oil

Nothing new here, sad to say

Volvo V70 - Person changing the oil cannot tell how much oil drained out? Then I have been operating under the wrong assumption for a long time. From people changing oil saying things like this to me over the years I assumed they all could tell. No? Maybe some places they can tell and some can’t?

GeorgeSanJose - thanks for the explicit info, this helps a lot.

Unrelated question - I may move to Iowa soon, anything I should be aware of? You know, like the salt in midwest will eat away undercarriage.

“I topped off tank too much and ran a bit of fuel down the side”

This implies that you always top off the tank. That is a very bad practice, you should stop when the nozzle first clicks and turns off. See GeorgeSanJose comments above.

My 2006 matrix uses no noticeable amount of oil between 5000 mile changes.
And yet I check the level every 1000 miles. Cheap insurance.
The Owner’s manual say to check the oil every time it’s refueled.
Also, every time I get work done at a shop I do a quick inspection of their work before I leave the lot.
I do my own oil changes, but I suggest when you get an oil/filter change you should check that the level is full then look under the car for drips while it’s idling.

Any engine will begin to use a lot of oil if it’s neglected. A few will use a lot of oil anyway. Toyota is not among those that do. I’ve owned a number of Toyotas starting in 1976, some I’ve put hundreds of thousands of miles on, and I’ve never had one use excessive oil. My current one has 233,000 miles and doesn’t use excessive oil. My “late” '89 Toyota pickup had 338,000 miles on it and didn’t burn excessive oil.

Iowa and all the Midwest, salt will depend upon where you live. In cities, they use a lot of salt or similar chemicals. In lesser populated areas, not so much.


I disagree about Toyota being among those manufactures that is NOT not for oil consumption

I’m not saying that every 4-banger is going to have the problem

I’m saying it’s not rare . . . not at all

Once again we’re going to have to disagree on this. But I cannot sign off without saying that I get tired of hearing everyone with a Toyota told that Toyotas have a serious oil consumption problem. It simply ain’t so. You’ll have to understand if everytime you tell an OP that I post the opposing view. It’s nothing personal.


I’ve had several Toyotas that had sky high oil consumption from day one

And they were excellently maintained

“It simply ain’t so.”

I have a different opinion :smiley:

Fair enough. :smile:

The 1ZZFE motor in these cars are known to use oil. Some do and some do not. I have a 1998 Prizm same motor, and oil has been changed religously @ 3000 miles. It has 120,000 on it, and the oil consumption is none. After 3000 still gold colored. The oil drain holes on the piston skirts are to small on these engines. Oil change neglect will cause coking of the rings ( dirty oil cakes to the rings ) then you start getting oil blowing through the exhaust destroying the catalytic convertor - CEL comes on etc. etc. Still though not sure why some do it and some do not. I so far have been one of the lucky ones :slight_smile: