One problem related to power assist brake vacuum hoses, lines/piping, and fittings has been reported for the 2003 Volkswagen Jetta. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Volkswagen Jetta based on all problems reported for the 2003 Jetta.
June 24th, while I was driving my four month old 2003 Jetta tdi on the the highway at a 70mph, the cruise control failed to engage. After the car had stopped and began moving again the cruise functioned properly. Two days later on June 26, 2003, while in lunch hour traffic-with a CO-worker in the car the brakes automatically engaged by themselves at 40 mph. We stopped on a dime and were almost rear ended. This occured over 10 times before we got back to the office (we were less than two miles away). Dealership is replacing brake booster and master cylinder and I have requested full warrenty on new brake system from Volkswagen of America. This is a potentially serious flaw that could have eaisly caused bodily injury. I have yet to learn if there is a track record of the brakes failing on the 2003 designs but wanted to begin a documentation record.