If you had to come back as an EFI sensor, the mass airflow sensor would be a good one to be. A MAF sensor gets bathed in cool, fresh air all day--quite the opposite of being a Jaguar oxygen sensor. As a Jaguar oxygen sensor, you'd be hammered by hot, dirty exhaust all day long, and you'd have to test every last bit of it. That's basically what your Jaguar oxygen sensor does: It samples your exhaust gas to determine how much fuel and air remains after the combustion process. If the Jaguar oxygen sensor doesn't like the outcome, it tells the computer to adjust the mixture. Based on this short description, it's probably obvious that the Jaguar oxygen sensor plays an important part in how well your vehicle runs. If your Jaguar O2 sensor isn't sending the correct information back to the car's computer, you get rough running, poor fuel economy, and you can burn up your catalytic converters. Since that sort of damage gets expensive fast, replace your Jaguar oxygen sensor at the first sign of trouble. The Jaguar oxygen sensor isn't a dealership-only item--you can buy a brand new Jaguar oxygen sensor right here--and it's not particularly expensive in light of what it does. So if you've had a Jaguar oxygen sensor replacement recommended to you, take heed. But you don't have to swallow retail pricing on your new Jaguar oxygen sensor. Buy a new Jaguar oxygen sensor right here and save some money today.