I have a 2002 tacoma v6-- CHECK light came on and stays on, what does it mean? It is still running OK

This means that it needs to get the codes scanned as this will point to developing problem that needs attention. If the vehicle is running ok, then it is usually an emissions problem.

There are two separate warning lights. One says " check engine " the other says "service engine soon" If the "check engine" light comes on The first answer is correct and you need to have a scan done to find the cause. Now if the "service engine soon " light comes on , you just need to check all your fluids, (oil, water etc.)

The older vehicles like my 95' truck has an SES light, meaning the same thing as the check engine light. Another one is a MIL light meaning Malfunction Indicator Light which = the Check Engine Light also. You will have separate lights that come on for your different fluids if they are low.

In case you didn't know you can get your codes scanned for free at one of the national chain auto parts stores.