The car has 127K miles and the Check Engine light is on again for the third time since Dec 05. The first time I was told the thermostat needed to be replaced because the engine wasn't getting hot enough. Cost -$500. The second time was in May 06, and the O2 sensor was bad. I took it to a tech school's auto shop and had diagnostics run and was told there were two O2 sensors on the car adn that I should have both replaced because the 2nd one would show up once the first one was replaced. The auto shop teacher recommended the same place I had gone the first time. The shop told me there was only one O2 sensor in my car and that the water pump should be replaced. Cost -$500. At the end of July the light came on again. Not having another $500, I have been driving the car back and forth to the bus stop and close errands, but I have to have emission testing done before the middle of Nov in order to renew my license plate. I'm hoping to get the school to run diagnostics again before I take it to the shop. If I really do have 2 O2 sensors and the diagnostics show it is now the 2nd one, I'm really going to be upset at paying another $500! I've asked several people and about half tell me I have two and the other half say there is only one. Anywhere I can find out for sure? I wouldn't know what to look for under the hood. I can check the oil and radiator, but not much beyond that. Any help is appreciated!