Why does the engine fault light always stay on?
3 Answers
Here are the reasons why the fault light always stays on: 1. Oxygen sensor malfunction. 2. Poor engine maintenance. 3. Use of low-quality fuel. 4. Poor combustion of the air-fuel mixture. 5. Dirty air filter. 6. Air flow sensor malfunction. 7. Spark plug carbon buildup. 8. Damaged water temperature sensor. 9. Engine misfire. Here are measures to prevent engine faults: 1. Regularly change engine oil and oil filter. 2. Maintain good crankcase ventilation. 3. Regularly clean the crankcase. 4. Periodically clean the fuel system. 5. Regular maintenance of the radiator. 6. Maintenance and cleaning of the fuel system.
I remember back when I drove an old car, the check engine light kept coming on – so annoying. The most common culprit was a faulty oxygen sensor. It controls the fuel mixture, and when it's off, the light comes on and fuel efficiency drops. It could also be a clogged catalytic converter not cleaning exhaust properly, triggering the light. Don't ignore it – last time I waited until the car started shaking, and it turned out to be misfires from worn spark plugs. Replacing them fixed it. Running it like this long-term wears out the engine – you could spend enough on gas to buy a new sensor. My advice: when the light comes on, borrow or buy an OBD scanner to read the codes. A code like P0420 directly tells you what's broken, no guessing needed. Fix small issues fast to avoid compounding problems. Get in the habit of checking under the hood monthly for loose connections – simple maintenance extends your car's life.
I've dealt with countless check engine light issues and here are some practical steps. First, check the basics: Is the fuel cap tightened properly? A loose cap allows air leakage, causing the system to falsely detect a leak and trigger the light. Then try restarting the engine – temporary errors sometimes clear up. If that doesn't work, use an OBD scanner to read trouble codes like P0171 (lean mixture) or P0300 (misfire), which point you to the faulty component. Simple fixes may involve replacing sensors, while complex cases could indicate ECU problems. Act promptly to avoid 20% increased fuel consumption or internal engine damage. Regular maintenance like using clean fuel and periodic fuel system cleaning prevents clogged injectors from triggering the light. These tips can save significant money and time.
