One problem related to gas recirculation valve (egr valve) has been reported for the 2009 Acura TSX. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Acura TSX based on all problems reported for the 2009 TSX.
In September 2008, I purchased a new 2009 Acura Tsx from an authorized Acura dealer in pennsylvania. After a few weeks of driving, I started to notice a knocking noise coming from the engine. The noise occurs consistently while accelerating (particularly when accelerating between 2000-3000 rpms while going uphill). Per the dealers instructions, I have used only premium fuel in the vehicle since the purchase date. I heard this knocking noise while driving the car throughout the winter; however, the noise has become progressively louder as the weather has become warmer (the noise is much louder when the temperature is above 60 degrees). I took the car into the dealer (where I purchased the car) today (4/24/09). One of the technicians rode along with me, and I was able to replicate the noise for him. The technician acknowledged the noise and said that I shouldn't worry about it, that it is a normal characteristic of the car. I received a receipt from the dealer stating this in writing. Although the dealer states that this is a normal noise, it's not something I've ever heard in any other car before (including my last car, which was also an Acura) and I'm concerned that this problem may actually cause damage to the engine over an extended period of time. There are many other people that have reported the same problem on this website, and on many of the Acura discussion boards. My next step is to take the car to another Acura dealer to get a second opinion, and also to contact Acura's corporate customer service department. Any assistance the NHTSA could provide to the group of people that are experiencing this problem would be greatly appreciated.