What Causes the Engine Fault Light to Illuminate After Using Low-Quality Fuel?

[GeorgeLynn]

Using low-quality fuel can cause engine wear and trigger the fault light. In such cases, the fuel in the tank should be drained, and the tank thoroughly cleaned. After cleaning, standard-compliant gasoline should be refilled. Apart from fuel quality issues, there are six other common factors that can cause the engine fault light to illuminate: Sensor Malfunction: Sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors, when damaged, poorly connected, or experiencing signal interruptions, prevent the car's ECU from accurately obtaining engine data, leading to the illumination of the engine fault light. Poor Combustion of Air-Fuel Mixture: Poor combustion can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the fault light will illuminate as a warning. Issues like spark plug failure, ignition coil failure, fuel pump failure, or fuel line blockage can all lead to poor combustion of the engine's air-fuel mixture. Turbocharging Issues: Problems with the intake boost piping or turbocharger can also trigger the engine fault light. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake Issues: If the car's intake system is compromised, it can lead to engine pipe blockages, and in severe cases, the engine fault light may illuminate. A dirty or uncleaned air filter can cause intake problems. Exhaust Issues: Exhaust system faults can also cause the engine fault light to illuminate. Common causes include rear oxygen sensor failure, catalytic converter issues, exhaust camshaft and bearing wear, with the catalytic converter being the most frequent culprit. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or fuel system malfunctions can all lead to catalytic converter failure. Anti-Theft System Malfunction: If the car's electronic anti-theft system fails or if the anti-theft controller is incompatible with the engine's electronic controller, the anti-theft system can prevent the engine from operating normally, accompanied by the illumination of the engine fault light.

[KyleMarie]

I remember one time after refueling at a small gas station, the engine malfunction light came on immediately. The substandard fuel contained too much gum and impurities, which clogged the fuel injectors, resulting in poor gasoline atomization and incomplete combustion. At this point, the oxygen sensor detects abnormal exhaust emissions, and the ECU computer receives the signal and lights up the warning light. The car feels sluggish when driving, and the throttle response is weak. It's recommended to add a bottle of fuel system cleaner immediately and choose a reputable gas station next time. Long-term use of substandard fuel can also damage the catalytic converter, and the repair cost can be shockingly expensive.

[GageFitz]

The most common cause for the engine warning light to illuminate is fuel quality issues. Low-quality fuel with insufficient octane can cause abnormal vibrations detected by the knock sensor, triggering the vehicle's computer to issue an alert. Fuel with high water content is even worse, as the combustion in the cylinders produces water vapor, causing the oxygen sensor readings to fluctuate wildly. Once, after refueling, my engine light came on, and the mechanic said the piston tops were covered in carbon deposits. Now, I only fill up at Sinopec or PetroChina stations to avoid costly repairs later.

[Jose]

I know this issue well. Poor-quality fuel can suffocate a car. Impurities in the fuel clog the injectors, leading to incomplete combustion that gets flagged by the exhaust temperature sensor. The air-fuel mixture goes off balance, disrupting the air-fuel ratio. When the engine control module receives abnormal signals from various sensors, the warning light pops on instantly. With experience, sometimes after finishing that tank of fuel and switching to good-quality fuel, driving another few dozen kilometers can make the light turn off by itself.