2003 Explorer XLT Runs Rich

[2003ExplXLTOwner]

Greetings!

Any conjecture on my Explorer's running rich? The mechanic checked the codes and it indicates "running rich", but the plugs and coils are functioning just fine. I was driving it over the weekend and the "Service Engine Soon" light illuminated and stayed on, but upon driving on a freeway incline, the light blinked for less than 60 seconds, then permanently stays illuminated. Speculation or recommendations, anyone?

 

[Mr. Blue]

Might be a bad injector, not sure if that would cause a check engine light though.

 

[2003ExplXLTOwner]

Thanks. I'll check it out.