What would cause my check engine indicator light to come on?

The check engine light can come on for multiple reasons. The easiest thing you can check on your own is your fuel filler cap: is it securely fastened? If not, the evaporative emissions system can detect a leak due to a loose gas cap and turn the light on. Diagnostic testing performed by a qualified technician with proper diagnostic equipment and reference material is required to see what trouble code has been set in the engine's computer that has turned the warning light on. The test will give clues as to what concerns are present and where to check further. Your concern can be fuel, spark, air or emissions related.