I have a 2011 Touring 200 Convertible. The MIL came on Saturday--it is NOT flashing, but holding steady. When I go through the menu system, it reads - 'System OK'
I have done the following:
- Tightened the gas cap;
- put in brand name gas (Shell)
- inflated tires to 35-37 psi
- Turned key ACC-ON-ACC-ON for diagnostics, and got only 'dOnE' with MIL still on, but no numeric code.

I am planning to bring it to the dealer, but I guess I'd like to have a better idea what the problem may be before I do.

Thanks in advance.

 

In most states, they'll check it for free at Autozone.

 

An Update: I brought the car to the dealership, and as they got ready to run the diagnostics, the MIL light went out. After that, they found nothing wrong. The working theory was that the gas cap had been loose at some point, and after I tightened it, it took a couple of running cycles for the system to reset itself.

 

I'm not sure if it works for the newer models.. In any other case: Unscrew the minus cable under the hood; wait for a minute, run the engine, then.