in addition to the oil light flickering at idle, the other problem that has been driving me crazy is the check engine light. It came on before I sent the car with my daughter to school last fall and because I was working so much I took the car to my trusted indi Volvo mechanic. I asked him to check on the check engine light, that it was throwing a 02 sensor code, but the O2 sensor was only 12,000 miles old on a 158,000 mile car. Well, when I returned, he had replaced the 02 sensor, wires and plugs, timing belt,etc, etc. I was taken aback, because I was anticipating a $300 bill for the timing belt and it was nearly a $1000, but at least it was all fixed, right? Well, when my daughter drove the car to school (a 3 hour trip) the check engine light came back on. When she came back this summer, I checked the diagnotic unit and it's throwing an 02 code. Clearing the codes will turn off the light until the next time the car is started and then the light goes back on. Any idea what could do this? Thanks in advance, Greg