'American Idol' Bikini Girl -- Charged with Drunk Hit-and-Run

Katrina Darrell -- the girl who infamously auditioned for "American Idol" back in 2009 wearing just a bikini -- has been charged with hit-and-run while driving under the influence ... TMZ has learned

According to the charging docs, obtained by TMZ, Katrina has been charged with one count of DUI, and two counts of misdemeanor hit and run.

If convicted on all counts, she faces up to 2 years behind bars.

TMZ broke the story -- Katrina was arrested last month after allegedly running a red light and smashing into another car. According to police, Katrina attempted to flee the scene ... but was pulled over down the street by a cop who heard the crash.

Back at the police station, an officer administered a breathalyzer -- and Katrina blew a .15 and a .17 ... roughly double the legal limit in California.