How to Eliminate the Engine Malfunction Light on a Focus?

[MacManuel]

When the engine malfunction light is on, you can follow these steps: First, check whether the engine is running normally and if there are issues such as shaking or black smoke. If so, avoid restarting the engine. Particularly, do not restart if the red light is on. If the engine can start, 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 car will perform a self-check after powering on. Wait for 5-10 seconds and observe whether the malfunction light on the dashboard turns off. If the 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 code, identify the problem, and perform targeted repairs. There are seven main reasons why the engine malfunction light may illuminate: 1. Sensor failure: This includes sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors. If these sensors are damaged, have poor contact, or interrupted signals, the car's ECU cannot accurately obtain engine data, triggering the malfunction light. 2. Fuel or oil quality issues: If fuel or engine oil not meeting the manufacturer's specifications is used, it may cause engine wear and trigger the malfunction light. 3. Poor combustion of the air-fuel mixture: This 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. Causes include faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines. 4. Turbocharging issues: Problems with the intake boost pipes or turbocharger can also trigger the malfunction light. The most common issue is turbocharger damage, often accompanied by oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. 5. Intake problems: Clogged engine intake pipes can lead to serious issues, including the malfunction light turning on. A dirty or uncleaned air filter can cause intake problems. 6. Exhaust problems: Exhaust system faults, such as rear oxygen sensor failure, catalytic converter issues, or exhaust camshaft and bearing problems, can trigger the malfunction light. The catalytic converter is the most common culprit, often due to leaded gasoline, improper lubricant additives, physical damage, or fuel system faults. 7. Anti-theft system failure: If the car's electronic anti-theft system malfunctions or the anti-theft controller is incompatible with the engine ECU, the engine may not operate correctly, and the malfunction light will illuminate.