3:13 PM PT -- Law enforcement sources tell TMZ Karen was released on a $500 bond. Also ... we're told the repo man never got a hold of that Maserati.

"Love and Hip Hop: Atlanta" star Karen King walked into court to deal with 1 case this week, but never left ... 'cause she was arrested for an entirely different one on the spot.

Law enforcement sources tell us Karen was in court Monday to deal with her pending identity fraud case when she was taken into custody. We're told deputies hauled her off when the court clerk announced there was an outstanding warrant for her arrest ... for allegedly skipping car payments on a Maserati. 

As we reported ... Karen stands accused of skipping months of payments on the Maserati she bought in 2014, which led to a judge signing off on the warrant back in October. She'd been MIA ever since. 

No word yet if the repo man got his hands on the whip.