Poll of the Day > Just had to replace the catelytic converter

(+) Yeah! (+)

And the check engine light came back on 4 days later. I'm starting to think it was only the o2 sensors from the beginning. Why is it the check engine only comes on when you have to get an emissions test?

Because the check engine light used to mean any number of things (including running out of windshield wiper fluid) in older cars, but everyone ignored it.

So in a lot of newer cars, the only thing the engine light indicates at all is emissions problems.

The last time my car's engine light came on it was definitely an O2 sensor problem.

the last time my engine light came on my engine threw a rod

The last time my check engine light came on, my purge control valve needed replacing.

I bought one of these: https://www.amazon.com/gp/product/B00PJPHEBO

And Torque Pro for my phone: https://play.google.com/store/apps/details?id=org.prowl.torque

And now I can read the error codes on any modern car and clear them, all for about $20 total.

And here's what I use to read the error codes on my OBD-I Chevy Caprice:

https://gamefaqs.gamespot.com/a/user_image/4/3/1/AAQwHjAAEuG3.jpg

(You unbend a paperclip and use it to jumper two of the pins on the diagnostic port, then turn the key to run, and the CEL will flash the error codes)

I had an evap problem on my last car and after taking it to 3 shops, they couldn't fix it. Ended up getting a $20 sensor to clear all the codes, drive around for about 20 miles before getting it inspected (so it would reset 2 of them), then after it passed inspection driving it away and having the check engine light come back on. I did that for like 5 years before I got rid of the car. Then the next owner did that for another 3 before junking it.