One problem related to water pump has been reported for the 2011 Hyundai Sonata Hybrid. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 Hyundai Sonata Hybrid based on all problems reported for the 2011 Sonata Hybrid.
We were driving on i81n in virginia when it sounded like we were driving over gravel. I thought it could have been a tire. Found tires were ok. Waited to pull out safely. Seconds after we entered i81n, we began to lose power, a/c and a warning light indicating to check hybrid system came on in message board. We pulled off at exit 277n and had enough power to find a safe place to pull over. I discovered that the serpentine belt was shredded. We were towed to a Hyundai dealer where the car sat overnight on 9/6/15 until service opened on 9/8/15. The serpentine belt was replaced as well as the water pump belt which was also damaged. The mechanic informed me the new belt was not running true on the tensioner and a ridge had formed on the outside surface of the tensioner. My opinion is that the part was defective because the belt was not running true.