Your internal combustion engine must have both fuel and air in order for it to work properly. Your 1996 Lexus Rx300 has an oxygen sensor to measure the proportion of oxygen in the gas that is in your engine. It then takes that monitored information and feeds it to the computerized Electronic Control Unit (ECU). Essentially, an oxygen sensor helps to determine if the fuel is too rich or not rich enough. A fuel that is too rich means that it contains too much fuel. A fuel that is no rich enough means that there is too much oxygen. When the oxygen sensor is doing its job properly, you get the best fuel economy possible, and the smallest amount of exhaust emissions possible. This one part could improve your gas mileage by as much as 10 to 15 percent. This automotive component ought to be replaced about every 100,000 miles. If the Bosch oxygen sensor that is in your Lexus Rx300 is replaced according to this given schedule, it will save you money in the long run by saving fuel, and keeping other exhaust parts in working condition. Auto part buyers deserve courteous service when buying dependable parts for their car or truck. Because you deserve that, we've built a 24/7 technical assistance call desk to help you with your queries. If you spot a lower price elsewhere, call us - we always beat any price advertised elsewhere.