What Causes the Engine Warning Light to Illuminate in a Peugeot 307?

[DelHazel]

The engine warning light may illuminate 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 connections, or experience signal interruptions, the vehicle's ECU cannot accurately obtain engine data, triggering the engine warning light. Fuel or oil quality issues: Failure to use the fuel and oil types specified by the manufacturer may cause engine wear, leading to the illumination of the warning light. 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. Issues such as faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines can cause poor combustion. Turbocharger problems: Issues with the intake boost piping or turbocharger can also trigger the engine warning light. The most common problem 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: Blockages in the engine's intake system can lead to the warning light turning on. A dirty or uncleaned air filter can cause intake issues. Exhaust problems: Exhaust system faults can also cause the engine warning light to illuminate. Common causes include faulty rear oxygen sensors, catalytic converters, exhaust camshafts, or bearings. The catalytic converter is most frequently affected, especially due to the use of leaded gasoline, lead/silicon-based lubricant additives, physical damage, or fuel system malfunctions. Anti-theft system malfunction: If the car's electronic anti-theft system fails or the anti-theft controller does not match the engine's electronic controller, the engine may not operate correctly, and the warning light will illuminate. Steps to take when the engine warning light is on: First, check if the engine is running normally and look for symptoms like shaking or smoke. If present, avoid restarting the engine. Note: Never restart the engine if the light is red. 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 depressing the clutch. The car will perform a self-check. After 5-10 seconds, observe if the warning light turns off. If the light remains on, visit a service center as soon as possible. Technicians can use a diagnostic tool to read fault codes, identify the issue, and perform targeted repairs.