2002 Toyota Rav4....check engine light""is

Here are two of the most common causes of the check engine light.

Most common, MAF ( mass air flow ), sensor. A faulty MAF prevents the computer from determining the correct fuel/air mix ratio.

Oxygen sensor. ( front and rear, front meaning before the catalytic converter, rear meaning after the catalitic converter. The front measures the fuel/air mix being sent through the catalitic converter, the back measures the emmisions and lets the computer know if any fuel/air mix ratios need to be adjusted. Both of these can trigger the check engine light.

I hope this helps you.