One problem related to gas recirculation valve (egr valve) has been reported for the 2006 Mercedes Benz C230. The most recently reported issues are listed below.
Zero issues with this car until now. This week, June 2013, the car has 78,000 miles on it. I pulled up to a stoplight off the freeway, and the car started sputtering like never before. The check engine light came on - for the first time ever. The car stalled and engine died. It restarted, but when I pressed the gas there was no power, traffic was coming up the off ramp fast, I had to flash my brakes to get them to notice something was wrong but it was a close call. The car sputtered into the middle of a busy freeway overpass intersection with my family on board and eager traffic behind me. It was a very scary moment because the car went from completely reliable and trustworthy to complete loss of power and instability. I sputtered back home, creating the same dangerous conditions at every intersection. I took the car to a Mercedes Benz shop the next morning. After a lot of testing it was determined that the intake manifold needed to be pulled to look deeper into the engine. Hours later they found that the problem was caused by a defective plastic bushing of the intake manifold which broke and was sucked into cylinder #4 and #3. This caused the valves to bend and compromised the integrity of the cylinders and valves, according to the mercedes qualified technician. There is extensive damage to the valves, and they don¿t know what all they¿re going to find once they pull the headers off. The cost to repair the car is $4,400, but it may even be higher. The cylinders have to be sent to a machine shop to see if they have any other issues as a result. Who knows what they'll find. The mechanics stated that Mercedes Benz is aware of this problem, that those moving plastic parts in the intake manifold are known to crack and cause problems and should never have been made out of plastic, but I don¿t see recalls on this obvious engineering & manufacturing defect.