One problem related to gasoline engine has been reported for the 2002 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Toyota Sienna based on all problems reported for the 2002 Sienna.
Idle control valve failure. Prevents car from idling correctly. Car will start and then cut off right after you drive off. Potentially causing you to get hit by other vehicles. This happened on my 2002 Sienna at 40k mile and continuously since. I know of 4 other people with this problem. My mechanic had about 10 or these defective parts in his shop and he said that he replaces these all the time on all the Toyotas. I took my car to the fremont Toyota dealer and the service rep said the failure rate was so high that there was a nationwide shortage for this part and that it would take 2 months for the part to be available. The dublin CA, Toyota dealer was also well aware of this problem of the idle control valve. It's a very dangerous situation for all operators of Siennas, camrys, and other totota vehicles with this idle control valve.