One problem related to gas recirculation valve (egr valve) has been reported for the 2006 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Toyota Sienna based on all problems reported for the 2006 Sienna.
Issue: my 2006 Toyota Sienna's ventilation system heats up even if setting at cold level. It caused the interior of the van to heat up uncontrollably and could cause heat exhaustion during hot summer days. The unwanted heat was traced from heat at the engine compartment enter the passenger cabin through the ventilation system. Due to insufficient insulated area at the engine compartment to the passenger compartment. It is extremely dangerous for young children in the vehicle during hot summer time. We noticed the issue during one of our summer vacation in 2007. We were stuck in heavy traffic for more than 15 minutes. Outside temperature was at a comfortable 75 degree, but the interior of vehicle feels like 90 degree. The air coming from the air vent is hot. I did some research on this issue, it turns out that Toyota fixed this issue on 2008 and later vehicles by adding insulation pad between the engine compartment and ventilation system. However, the Toyota dealership refuse to provide the fix to my van.