One problem related to loud engine noise has been reported for the 2004 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota Sienna based on all problems reported for the 2004 Sienna.
Driving about 15 mph through parking lot. . . An alarm sounded followed by a "loud noise" from the rear. This was followed by the car braking and pulling to the right. Engine did not stop. The car would only crawl when attempts were made to drive it. Any faster than 2-5 mph caused repeat of the event. No information lights were activated on the dashboard. Car was taken by flatbed to Toyota dealership. Access to the onboard computer by the service people at dealer did not reveal any faults. An attempted solution was to reprogram the abs module. This did not resolve the problem. At this time, the car remains at the dealership. Report filed with Toyota regional by both dealer and myself.