One problem related to engine noise has been reported for the 2006 Toyota Sequoia. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Toyota Sequoia based on all problems reported for the 2006 Sequoia.
While driving at 35 mph, the check engine light, vsc off light, and vsc trac light all came on at once, and the vehicle stopped accelerating, and I experienced a dramatic decrease in vehicle power. I drove the vehicle home noticing a drastic change in acceleration as the Sequoia would not accelerate normally; it would accelerate at a significantly reduced rate, topping out at 35mph on the flats and 16 mph on an incline, in addition, during start up, the engine makes a high-pitch vacuum noise, which drops off and normal engine sound returns. I have had the car diagnosed; error codes p2440, p441 and p444 are all present indicating a failure of the air injection pump. This is a known problem on Toyota Sequoias and tundras; however, Toyota has only acknowledged it on the 07-10 Sequoia by extending the warranty to 10 years and 150,000k miles for this part. It is clear from other posts on the NHTSA website and others that this problem also exists with the 2004-07 Sequoias as well. This is a safety issue that needs to be addressed before someone is injured, or worse yet killed.