Check engine light

It's possible, but it's also possible that the light is on because of a transmission code. You need to know the trouble code causing the light, and then you need to know the correct underlying reasons for that code.

If your check engine light is constantly on, or switching back on, I can promise you there is no problem. I owned an '02 Millenia for just under 5 years before it died on me, & that darn check engine light NEVER shut off! However, if it starts to flash, then there is a problem.