What Causes the Constant Illumination of the Mondeo Engine Malfunction Light?

[SanKendra]

The engine malfunction light may illuminate due to the following seven main reasons: Sensor Failure: The sensors mentioned here include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensors, etc. When these sensors are damaged, have poor connections, or their signals are interrupted, the vehicle's ECU cannot accurately obtain engine data, which may trigger the engine malfunction light. Fuel Quality Issues: If fuel and engine oil are not added as required by the manufacturer, it may cause engine wear, leading to the illumination of the malfunction light. Poor Combustion of Air-Fuel Mixture: Poor combustion can lead to engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Issues such as spark plug failure, ignition coil failure, fuel pump failure, or fuel line blockage can all cause poor combustion of the engine's air-fuel mixture. Turbocharging Problems: Issues with the intake boost piping or turbocharger can also cause the engine malfunction light to illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake Problems: If there are issues with the vehicle's air intake, it may lead to engine pipe blockages, and in severe cases, trigger the engine malfunction light. A dirty or uncleaned air filter can cause intake problems. Exhaust Problems: Exhaust system failures can also cause the engine malfunction light to illuminate. Common causes include rear oxygen sensor failure, three-way catalytic converter issues, exhaust camshaft and bearing failures, with the three-way catalytic converter being the most frequent. Using leaded gasoline, lead or silicon-containing lubricant additives, physical damage to the catalytic converter, or fuel supply system failures can easily lead to three-way catalytic converter problems. Anti-Theft System Failure: If the vehicle's electronic anti-theft system malfunctions, or if the anti-theft controller does not match the engine electronic controller, the anti-theft system can prevent the engine from operating normally, while also triggering the engine malfunction light. If the engine malfunction light is illuminated, follow these steps: First, check if the engine is running normally, looking for signs of shaking, smoke, etc. If such issues are present, avoid restarting the engine. Particularly, do not restart the engine if the red warning light is on. If the engine can be started, turn it off for 5-10 minutes, then without pressing the brake, press the start button once or turn the key halfway to the 'on' position without depressing the clutch. The vehicle will perform a self-check after powering on. Observe whether the malfunction light on the dashboard turns off after 5-10 seconds. If the malfunction light remains on, visit a service station as soon as possible to diagnose the issue. The service station can use a portable diagnostic tool to read the fault codes, obtain fault information, and perform targeted repairs.