What are the reasons for the OBD light to come on in a car?
2 Answers
The reasons for the OBD light to come on in a car are: 1. Engine sensor malfunction, abnormal operation of the sensor; 2. Dirty throttle; 3. Damaged spark plug causing the OBD light to come on; 4. Abnormal working pressure of the fuel pump; 5. Contaminated or damaged fuel filter; 6. Dirty or damaged three-way catalytic converter. The working principle of OBD: When an emission fault occurs, the ECU records the fault information and related codes, and informs the driver through the malfunction indicator light or the check engine light. OBD includes: 1. EGR; 2. Engine; 3. Particulate filter; 4. Catalytic converter; 5. Oxygen sensor; 6. Emission control system; 7. Fuel system.
That time my old car's OBD light suddenly came on, and I was startled thinking it needed major repairs. A friend told me common causes are issues with the emission system, like a faulty oxygen sensor or a loose fuel cap. I remember once after refueling, the cap wasn't tightened properly, and the light came on. If the light stays on after restarting the car, it might be a sensor malfunction or a problem with the catalytic converter. Exceeding emission standards can trigger the light, as required by national environmental regulations. I rushed to the repair shop, and the mechanic used a diagnostic tool to find code P0420—sure enough, the catalytic converter was aging. Regular checks on the air filter and fuel quality can help prevent issues. Don't delay repairs, or fuel consumption might increase and other parts could get damaged. Back then, I replaced the sensor and everything was fine. Simple maintenance can save a lot of hassle.
