It finally happened at around 85,000 miles my 2007 Lexus IS250 displayed the dreaded Check Engine Light and VSC. I had just changed the oil at the dealer a few weeks back and also replaced the rear axle and front bushings, then drove off and my dash lit up like a Christmas tree. I went back to the dealer and they determined the cause was a dead O2 sensor and leaking valve cover gasket. They believe oil dripping from the gasket fell on the O2 sensor and caused it to fail. Total bill? About $1,300. O2 Sensor - $600 Valve Gasket - $700 In addition to resolving the Check Engine light, I also had other maintenance and repairs. So total cost for the month was $ 4,050. Oil Change - $250 Rear Axle - $ 1700 Front Bushings - $800