software update?

welcome! sounds like he needed to update the amount of cash in his wallet.

so, he hasn't replaced the sensor? ask him for the trouble codes he pulled and post them here.

how many miles are on your car?

sometimes, the check engine light is just a loose gas cap.

 

is he a hybrid specialist?

 

You can clear the codes with an ODB2 adapter. Anyone can do it. Doesn't fix anything. Whatever triggered it will eventually trigger it again.

 

The ECM is the Engine Control Module, one of the several computers in the car. A "calibration file" is a bunch of tuning parameters Toyota develops and loads into the ECM. Sometimes they do identify ways to improve the calibration and improve how the engine runs, and they release updated calibration files.

If you have a laptop and Techstream (lots of posts in these forums about using that software, needs a little dongle from the laptop to plug into the car, some are less than $30), you can even check what calibration files you currently have (a geeky thing to do, maybe, but an easy way to confirm what your mechanic actually did).

For example, my Gen 3 engine calibration is currently 34715200, from which I can tell that no one has ever done the EGR system warranty repair on my car yet, because if they had, it would be at least 34715700.

Your mechanic might be able to tell you which calibration he loaded, and whether there was a service bulletin saying he should update to that version, and what issues it said it might solve.

Can you get him to tell you what the actual trouble code(s) was/were indicating the issue with the "gas tank emissions sensor"? That information might also help pin down which sensor he means. I'll guess he means the vapor pressure sensor, and yeah, the picture in the New Car Features Manual shows it on top of the tank, so the tank might have to come out to get to it.

But there's a whole section in the repair manual on how to pin down why pressure readings might be off, before being sure the sensor is at fault.

-Chap

 

when you go for an inspection these days, all they do is plug in and read the history. so, it doesn't matter whether you go with the light on or off.

if the calibration fixed it, you'll pass. if the computer says you need a new sensor, you'll fail.

 

If it's truly fixed.

My understanding is that if the codes were merely cleared then the emissions status will be in an indeterminate state until the car/engine has been run far/long enough for the computer to be sure any (now cleared) conditions are not obviously still present. Until then, those sensors won't report PASS even if the CEL is off.

 

Could be either. Easiest to know if you're the only one who ever touches the filler cap. A loose cap is obvious. If it was tight but throwing codes it could be defective.

The other thing about gas cap codes is that they don't immediately clear the CEL when you fix it. The car needs to go through a number of driving cycles after the fix before it clears. You can force clear, but then see my prior post.