DriverSide's Car Dictionary has the most comprehensive definitions of automotive terms. This auto glossary can help you decipher what your mechanic is fixing and what the purpose or function of the particular auto part or accessory is for. We have taken the mystery out of automotive service jargon, so that you don't have to.
Any number of devices that measures some engine factor and transmits a signal (i.e. reading) to the engine's computer. These can and do fail, and can muck up the way your engine runs in any number of ways, though thankfully they can often be tested with an ohmeter before you start--to great expense--replacing parts.