What Causes the Engine Fault Light to Illuminate in the VV7?

[DerekFitz]

The engine fault light may illuminate during power-on self-test or under other circumstances. The power-on self-test is an indication that the vehicle is monitoring the status of all sensors before driving. Generally, if the engine is not started after power-on, the light will turn off automatically after about 3 seconds. In other cases, if the EPC indicator light remains illuminated after the vehicle starts, the main causes may include faults in the engine intake system, throttle valve, fuel system, engine itself, ECU control unit, or brake lights. Below is a detailed explanation of each possible fault: Sensor Issues: Sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors may become damaged, have poor contact, or experience signal interruptions. When the car's ECU cannot accurately obtain engine data due to these issues, the engine fault light will illuminate. Solution: Seek professional inspection and repair at a service center promptly to eliminate potential safety hazards. Maintenance Issues: Poor engine maintenance is the most common cause of the engine fault light. Vehicles have specific maintenance cycles, and failing to adhere to them, combined with poor driving habits, can increase the engine's operational burden, eventually triggering the fault light. Solution: Follow the maintenance schedule in your vehicle's manual, including time or mileage intervals, to ensure comprehensive maintenance and rule out non-maintenance-related issues. Fuel Quality Issues: This refers to both fuel and engine oil. Vehicles require specific fuel grades and types of oil (semi-synthetic or fully synthetic). If the wrong fuel or oil is used over time, it can cause engine wear and trigger the fault light. Solution: Always use the recommended fuel grade and engine oil type for your vehicle. Poor Combustion of Air-Fuel Mixture: Faulty spark plugs, fuel pump issues, or clogged fuel lines can lead to poor combustion. This results in engine carbon buildup or knocking, which the oxygen sensor detects and reports to the ECU, triggering the fault light. Intake Issues: Engine combustion requires proper air intake. A dirty or clogged air filter can restrict airflow, leading to engine issues and the fault light illuminating. Solution: Regularly clean or replace the air filter to ensure proper intake system function. Turbocharger Issues: Problems with the intake boost system or turbocharger can trigger the fault light. Common issues include turbocharger damage, oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black exhaust smoke. Solution: Visit a 4S shop to inspect and replace the turbocharger if necessary. Repairs are often not cost-effective, so replacement is usually recommended. Exhaust Issues: Faults in the rear oxygen sensor, catalytic converter, or exhaust camshaft and bearings can trigger the fault light. The catalytic converter is particularly prone to damage from impacts or fuel system issues. Solution: Use lead- or silicon-based lubricants to maintain and clean the catalytic converter. Anti-Theft System Issues: If the electronic anti-theft system malfunctions or the anti-theft controller is incompatible with the engine ECU, the engine may not operate properly, and the fault light will illuminate. Solution: Seek professional diagnosis and repair at a service center, as this issue cannot be fixed individually. Engine Misfire: When one or more cylinders fail to function properly, the vehicle may experience power loss, difficulty starting, or unstable idling. Solution: Identify and replace faulty cylinder components. If internal engine damage is detected, a major repair at a service center may be necessary.