What happens when an oxygen sensor fails?
3 Answers
When an oxygen sensor fails, the following symptoms may occur: the vehicle's engine malfunction indicator light turns on, unstable idling, insufficient engine power, sluggish acceleration, and black smoke from the exhaust. The causes of oxygen sensor failure include: 1. Ceramic element of the oxygen sensor cracking; 2. Heater resistance wire burning out; 3. Internal wiring of the oxygen sensor breaking or disconnecting; 4. Engine control unit malfunction. The oxygen sensor uses a ceramic sensing element to measure the oxygen potential in the vehicle's exhaust pipe, calculates the corresponding oxygen concentration based on chemical equilibrium principles, and achieves the purpose of monitoring and controlling the combustion air-fuel ratio to ensure product quality and compliance with exhaust emission standards. It is a critical measurement component.
With over a decade of car repair experience, I can tell you that a faulty oxygen sensor makes driving extremely noticeable. The engine wheezes like a drunkard, idles so rough it numbs your hands, and jerks during sudden acceleration. The most frustrating part is the fuel consumption – the dashboard shows an extra 2-3 liters burned per 100 kilometers, as if the fuel tank were leaking. The exhaust pipe either emits black smoke or a rotten egg smell, definitely failing emission standards. My advice: if your car acts up, scan the trouble codes immediately. Veteran drivers know this tiny component can drain your wallet through wasted fuel and might even destroy the catalytic converter, leading to terrifying repair bills.
Last time my car's engine yellow light came on, and the diagnosis showed the rear oxygen sensor was dead. Besides the warning light, I could clearly feel the exhaust pipe sound was muffled, and during cold starts, the exhaust sounded like an asthma patient coughing. The 4S shop said it could cause an air-fuel ratio imbalance, incomplete gasoline combustion, and in severe cases, even the spark plugs could get clogged with carbon deposits. Now that annual inspections strictly check exhaust emissions, a faulty sensor will definitely cause a fail. Replacing it with an original part costs nearly a thousand, but delaying the repair could easily ruin the catalytic converter, making the repair even more painful later.
