Exhaust Leaks, O2 Sensor Failure, and Emissions Codes
A failing oxygen sensor makes the car run noticeably worse: the check engine light comes on, fuel economy drops 10–20%, the engine idles rough, and acceleration feels flat or jerky. You might also smell sulfur from the exhaust. The quickest first move is to scan the OBD2 system—most auto parts stores do it free—and write…