Unfortunately a simple dash warning light is just too generic to pin down to one thing. Honestly, your first reference should be your owners manual. It will give a more accurate indication of what system might need attention.
Usually dashboard "idiot lights" will indicate you need to check some fluid level such as oil, water or brake fluid. My Mercedes alerts when the washer fluid is low. So, again, check your owners manual.
Do you have gauges? Does anything look amiss? Some vehicles can indicate when something is out of tolerance, such as worn brakes. Or perhaps even as silly as a gas cap being loose, in the case of vapor recovery systems.
Find a friend that has a OBDII scanner (available at Autozone, NAPA, etc). The code, or codes, thrown can give a better indication of what is wrong rather than someone just guessing.
Please report your findings.
Kevin