Tony McGahan's side trailed at the interval, 18-10, despite Doug Howlett's first-half try, but scores from Peter O'Mahony and Will Chambers brought them back into contention.
Then O'Gara, who landed another decisive drop goal to down Northampton last week, kept his cool to post the winning points from 40 yards, but insisted there is plenty more to come from Munster.
"I did enjoy it. It was nicely struck but I think we probably shouldn't have put ourselves in that position," said O'Gara - who converted all three tries as well as a penalty.
"I think we were good at times and poor at times so we have plenty of areas to look at. The most important thing is its two wins out of two.
"This is a huge competition for us and maybe a year ago I think we would have crumbled in that situation."
Meanwhile Ulster suffered a 20-9 Pool 4 loss to Leicester after failing to score after the interval.
Former Tigers fly-half Ian Humphreys kicked all of Brian McLaughlin's side's points as they went in at half-time at 9-9.
Connacht prop up Pool 6 after going down 36-10 in their first ever Heineken Cup home match against four-time competition winners Toulouse, who conceded a second-half penalty try.
Welsh outfit Ospreys were held 26-26 in Treviso after 19-year-old replacement fly-half Matthew Morgan salvaged a Pool 5 draw with a last-minute penalty.
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