What are the reasons for the continuous illumination of the car engine warning light?
2 Answers
The engine warning light may stay on due to the following 7 main reasons: Sensor malfunction: This includes sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors. When these sensors are damaged, have poor contact, or experience signal interruption, the car's ECU cannot accurately obtain engine data, triggering the warning light. Fuel or oil quality issues: Failure to use the fuel or engine oil as recommended by the manufacturer may cause engine wear, leading to the warning light activation. Poor combustion of the air-fuel mixture: This can result in engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the warning light will illuminate as a warning. Issues such as faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines can cause poor combustion. Turbocharging problems: The intake boost pipe or turbocharger can also trigger the engine warning light. The most common issue is a damaged turbocharger, accompanied by symptoms like oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: If the car's intake system is compromised, it may lead to engine pipe blockages, and in severe cases, the engine warning light will turn on. A dirty air filter that hasn't been cleaned regularly can cause intake issues. Exhaust problems: Exhaust system faults can also activate the engine warning light. Common causes include issues with the rear oxygen sensor, catalytic converter, exhaust camshaft, or bearings. The catalytic converter is most frequently affected, especially when using leaded gasoline, lead- or silicon-containing lubricant additives, physical damage to the converter, or fuel system malfunctions. Anti-theft system malfunction: If the car's electronic anti-theft system fails or the anti-theft controller doesn't match the engine ECU, the system may prevent the engine from operating normally, with the warning light turning on as well. If the engine warning light is on, follow these steps: First, check if the engine is running normally. If there are issues like shaking or smoke, avoid restarting the engine. Note: Never restart the engine if the red warning light is on. If the engine can start, turn it off and wait 5-10 minutes. Without pressing the brake, press the start button once or turn the key halfway to the 'ON' position (without pressing the clutch). The car will perform a self-check after powering on. Wait 5-10 seconds to see if the warning light turns off. If the light remains on, visit a service center as soon as possible. Technicians can use a portable diagnostic tool to read the fault code, identify the issue, and perform targeted repairs.
That check engine light keeps coming on, and I've personally encountered it many times. The most likely cause is a faulty oxygen sensor. It's responsible for monitoring exhaust gas composition, and if it malfunctions or gets coated with carbon deposits, the computer will mistakenly think there's an engine problem and keep the light on to alert you. Another common issue is a clogged catalytic converter - when exhaust can't escape properly, system pressure builds up and triggers the constant warning light. Fuel system problems shouldn't be ignored either, like clogged fuel injectors or a failing fuel pump, which can cause air-fuel mixture imbalance. Ignition system failures such as worn spark plugs or bad coils can also trigger this warning. I recommend scanning for trouble codes with a diagnostic tool ASAP. Don't delay, or the engine might overheat and get damaged or even completely stall out. It's both fuel-wasting and dangerous. Best to have a professional repair shop do a thorough inspection.
