Robbie Kydd and Luke Myring missed two shots at goal each - three of them routine chances - as Saints failed to capitalise on a promising opening to the second half.
Mark Robinson and Paul Tupai crossed for the home side who won the try-count 2-0 but Andy Goode's near-flawless marksmanship handed Leicester a 15-10 triumph at Franklin's Gardens.
"We were poor and I appreciate that if Northampton had kicked their points we would have lost," said Howard
"We won, it wasn't pretty and we're not overly proud of it. But we've come to Northampton and ground out a win in a week when we've hardly had any preparation time. We'll take it.
"We started with a lot of passion with some big hits going in but we let them into the game with their try. It was a soft try but their second was lovely."
Saints produced some remarkable second-half defence to keep Leicester from extending their lead with Ben Cohen tackling Scott Bemand when the Tigers scrum-half was over the line the highlight.
But the visitors could only blame themselves for one chance that went begging with Leon Lloyd overlooking a three-man overlap to go it alone.
"We could have closed the game out significantly better than we did, we weren't bright. But I wasn't overly worried about losing the match for the majority of it," he said.
"If Leon Lloyd had put away that three-on-one or Scott Bemand had scored then we'd have been away. If I was Paul Grayson I would be filthy after scoring two tries only to lose."