Bayern, beaten by Borussia Moenchengladbach last week for their first loss under coach Jupp Heynckes, moved on to 32 points, with RB Leipzig stuck on 26 after crashing to a 4-0 loss at Hoffenheim.
Borussia Dortmund managed a 1-1 draw at 10-man Bayer Leverkusen and have now failed to win since late September in the Bundesliga, leaving coach Peter Bosz under pressure.
Schalke 04 missed the chance to go second after twice taking the lead against bottom club Cologne but eventually drawing 2-2 to stay third on 25.
Chilean Arturo Vidal headed Bayern in front in the 17th minute and the hosts thought they had scored again through Robert Lewandowski but his effort was ruled offside after a video replay.
Hanover missed the chance to level after Niclas Fuellkrug's penalty was saved by Sven Ulreich but they made amends through Charlison Benschop in the 35th.
Bayern retook control after the break with Frenchman Coman, who came back last week from injury, drilling in from a tight angle. He forced Martin Harnik to bring him down in the box, allowing Lewandowski to grab his 14th league goal of the season with a well-taken penalty.
"I am satisfied," said Heynckes, whose team face Paris St Germain in the Champions League next week. "Thomas Mueller returned after a long time out, Coman was out for two weeks, Jerome Boateng is also back in form."
"Overall it is all good news and I am optimistic about our upcoming games," added the coach.
Leverkusen were superior and hit the bar with Kai Havertz's glancing header minutes after Dortmund's Maximilian Philipp was carried off with a knee injury.
Kevin Volland netted for the fourth straight game for Leverkusen in the 30th minute, with Dortmund also losing Gonzalo Castro to an ankle injury after a reckless challenge from Wendell, who was sent off.
Dortmund, who squandered a four-goal lead last week to draw 4-4 with Schalke, dug deep to level through Andriy Yarmolenko in the 73rd minute but despite a frantic finale failed to get the winner. They dropped to sixth on 22 points.
(Reporting by Karolos Grohmann, editing by Ed Osmond and Clare Fallon)
