I just bought my DTS 06 in April for the last three months the check engine lights comes on and throws an Oxygen Sensor code. It stays on for a few days and goes off. I had all three sensors replaced and two weeks later it came back on. I took it to the dealer and they could not figure it out why it comes on and goes off. They checked the sensors and they are testing fine. I love my car but if I can't figure this out I would have to think about getting rid of it.