Oxygen sensors not only help your car run smoothly and efficiently, they are also a vital smog component. All modern vehicles should have an oxygen sensor placed within the exhaust system. The sensor monitors the exhaust and tells the computer about the richness of the fuel mixture and whether or not adjustments need to be made. Failures can happen for mechanical reasons or from bad wiring and electronic components. A bad oxygen sensor can cause your car to fail a smog test in three of the following ways.
The check engine light stays on
Oxygen sensors are a common cause for triggering a check engine light. If your check engine light is on, your car will fail the smog test even if a smog component is not the reason for the failure. The appearance of a check engine light accompanies codes which can be read by a technician. These codes, along with an inspection by a mechanic, will confirm if it is an oxygen sensor failure. Failure rates and intervals for oxygen sensors vary between type of sensor and the vehicle model.
Poor fuel mixture
Since the oxygen sensor regulates the fuel mixture of your car, it is more likely to run too rich or lean when the sensor fails. Cars that run too rich will read high in hydrocarbons while cars that are too lean many emit more carbon dioxide or nitrous oxide. Too much of any of those pollutants will result in a failed smog test. Cars that run too rich or lean may have performance problems or emit a rotten egg smell, especially after accelerating. Your fuel mileage may also suffer.
Damage to the catalytic converter
Failure to address oxygen sensors could result in damaging an expensive catalytic converter. The catalytic converter is located in the exhaust system and absorbs much of the hydrocarbons and other pollutants that get past the combustion chamber. When the catalytic converter fails, the car will, more likely, produce too many pollutants and fail the smog check. On top of failing the smog check, the car will not run if your catalytic converter gets completely clogged. . Catalytic converters are one of the most expensive components in many vehicles, so it pays to keep it from getting damaged.
Performing regular maintenance will help keep your car's oxygen sensor in good shape and lasting longer. Report any performance problems and have your technician run diagnostics. This way you can both keep your car running clean, save money not replacing expensive components or paying for repeated smog checks due to failures.
For more information, talk to a professional like West Coast Smog.