What Causes the Exhaust Fault Light to Illuminate?
2 Answers
Exhaust fault light illumination is caused by damage to the oxygen sensor in the three-way catalytic system or poisoning of the three-way catalytic converter. If this light comes on while driving, immediately reduce speed and proceed to the nearest service station for inspection. Below are specific details about the three-way catalytic converter: 1. Introduction: The three-way catalytic converter refers to a catalytic process that transforms harmful gases such as CO, HC, and NOx emitted from vehicle exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction. 2. Application: The core component of the three-way catalytic converter is a porous ceramic material installed in a specially designed exhaust pipe. It is called a 'carrier' because it does not participate in the catalytic reaction itself; instead, it is coated with a layer of precious metals such as platinum, rhodium, palladium, and rare earth coatings. It is the most important external purification device installed in a vehicle's exhaust system.
The most common reasons for the exhaust light to illuminate include oxygen sensor failure, catalytic converter issues, evaporative emission system leaks, or fuel system abnormalities. Having driven for ten years, I've encountered this several times. Once, the oxygen sensor failed, causing the engine computer to receive incorrect signals and fail to adjust the fuel mixture properly, leading to excessive emissions that triggered the light. A clogged catalytic converter can also keep the light on constantly—my experience is that early detection is cheaper, while late repairs are costly. Evaporative issues, like a loose fuel tank cap, are also common and can often be resolved by simply tightening it. In short, don't ignore it—it increases fuel consumption and pollutes the environment. I recommend using an OBD tool for diagnosis before proceeding with repairs.
