Thank you all for your help. Unfortuntely, I'm at the mechanics mercy. I also have a small leak from under the car near the passenger front seat side. It looks like antifreeze (???). It looks like the problem(s) could be a number of things- bad O2 sensor was replaced in the rear. Electrical problem? I'm wondering why some of those lights have appeared about three times in three weeks. Why would the odormeter reading disappear during that time (too bad it didn't lower the miles when it came back on!) Would you please clarify something for me - when the car is hooked up to the OBDII (or whatever you call it) what must be done to get the fault codes? Mechanic showed me the last time the rear O2 sensor bad. How are these codes cleared? Do you get a number of codes if there is more than one thing wrong? Do you get false results? I'm a single mom on a very limited budget and can't afford a new car......