my check engine light stays on

There are many possible causes for this. One of the most common is an improperly tightened gas cap. Shut off the car, remove the cap, replace the cap, and start the car back up. Other causes could be a dirty valve or even an oil leak. If the gas cap fix doesn't work, you may need to check with a mechanic.

Typically the above response is true, but not for Toyotas. If the vehicle is running fine and you dont feel anything wrong, it is probably either the converter or CO2 Sensors that are failing. I know from experience.

you should take it to toyota. It could be something serious or something simple

i dont know what year this thing is but if its ten years old or newer , you dont feel any thing wrong , and you dont have to pass an e-check any time soon then you have nothing to worry about its just your emissions sys. screwing up

Did you have the codes read and the light shut off before? It generally doesn't go away on its own. Take it to a parts store like autozone and most will read the trouble code and shut the light off for free.

Obd2

My engine light came on after Toyota dealership did the 120K service that changes plugs,etc. Paid them to have codes checked. They gladly offered to install a new catalytic converter. No guarantees it would work and double the price of a muffler shop. My mechanic said whatever burned up the converter could do same to the $2,000 new one. Advised to ignore light as long as gas mileage stable and running smoothly. I am currently at 180,000 miles.

wow. My mechanic at dealership installed a new computer, a new oil cover gasket , a new oxygen sensor, and still the light is on. I think maybe it is a simpler problem, like dust in the engine filter or a spark plug or throttle body cleaning. I did not have to pay because the light came on as soon as I drove it off lot after the initial repairs when I bought it. They are refinanicing another used car, but I love my 2004 used white Toyota and wonder if I should just have it checked by another mechanic. I would have to pay for this.

Check your air intake using a smoke machine to find any leaks in hoses.