To find them precisely:
* Consult a repair manual: A repair manual specific to your 1992 Cadillac Sedan DeVille with the 4.9L engine will show you the exact locations with diagrams. This is the most reliable method.
* Look under the vehicle: With the car safely supported on jack stands, examine the exhaust system carefully. The oxygen sensors are usually threaded into the exhaust pipes. They'll have wires leading to them, often bundled together. One will be upstream (before) the catalytic converter(s), and one (or more, depending on your specific Cadillac's emissions setup) will be downstream (after). The upstream sensor is generally more accessible.
* Online resources: While not as reliable as a repair manual, searching for "1992 Cadillac DeVille 4.9L oxygen sensor location" on websites like YouTube or forums dedicated to classic Cadillacs might yield some helpful visual aids or owner experiences. However, always cross-reference with a reliable source like a repair manual.
Important Safety Note: Working under a car requires proper safety precautions. Always use jack stands, never rely on a jack alone. Ensure the vehicle is stable and secure before you start working. Wear safety glasses and gloves.
Because of the age of the car and the variations in the specific configuration, visual confirmation under the vehicle is essential. A repair manual is the only truly reliable way to be absolutely certain.
