Check engine soon light is on, in my 2002 Lancher. What does it mean?
The yellow "Check Engine" or "Service Engine Soon" light is an informational indication to you to let you know that the computer has detected a problem with the engine that needs to be checked.
If a RED indication - this means that the there is a problem the requires immediate attention. This usually means shutting off the engine and stopping for the case of a RED oil, temperature, brake, etc message.
The yellow indication means that the engine has a problem that is not noticeable to you - at least at first - but left unchecked could result in costly repairs. Many of the problems associated with this YELLOW indicator are related to fuel & emmissions systems, such as faulty oxygen sensor, fuel sensor, mis-firing, low engine temperature, and much, much more. These can cause fuel economy to suffer and very hot exhaust components or even failure of the catalytic converter. Drive the car to wherever you're going - but make appointment to have it checked out. Many Auto parts stores such as Auto Zone will be happy to use their tool to "scan" the fault code stored in the computer. This code will help you narrow down the problem and potentially save you from having your mechanic simply tighten your gas cap (and yes - a loose gas cap can trigger this light!).
I hope this helps and good luck!
on Mar 01, 2013