One problem related to timing tensioner has been reported for the 2015 Volkswagen Jetta. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 Volkswagen Jetta based on all problems reported for the 2015 Jetta.
The timing belt tensioner went bad causing the timing chain to jump time at 72k miles. This did not cause any internal engine damage but did cost a ton of money. Apparently this is a common issue in older Jetta's, but it appears that the newer models just haven't been given enough time to screw up. It also had to have the high pressure fuel pump replaced due to failure. The car was stationary in my driveway and would not start.