The service-engine-soon or check-engine light on a car's dashboard means that there is a problem with some component of the car's electronic control system. Always check the vehicle's owner's manual as soon as a check-engine light or other indicator illuminates in the dashboard.
A flashing check-engine light has a much more serious meaning than a steady light. The flashing light could mean a catastrophic problem with the engine, catalytic converter or exhaust system. This light needs to be checked by a mechanic as soon as possible.
A steady check-engine light may indicate a problem as simple as the gas cap not being tight enough. It could also indicate a more in-depth problem with one of the car's complex systems. Some of these problems include a wet engine, a blown head gasket, bad oxygen sensors, problems with spark plugs or wires, cracked or loose hoses or manifolds or problems with the fuel injector's O-rings.
A car with the service-engine-soon or check-engine light needs to be hooked up to a computer for a diagnostic test of all the systems in the car. A mechanic can perform this evaluation and offer suggestions and solutions to solve the problem, as well as turning the light off.