The illuminated engine warning light signals that the engine control unit has detected a fault. In modern cars, the ECU continuously monitors sensors and operating conditions to maintain performance and reliability.
The most common causes of this warning are sensor faults. The oxygen sensor measures the oxygen level in the exhaust stream. When it fails, the engine runs less efficiently and fuel economy drops. Replacing the sensor is typically the remedy.
A second frequent issue involves the catalytic converter, which reduces harmful emissions. If the converter becomes clogged or fails to operate, engine power drops and fuel consumption rises.
A third common problem is a faulty mass air flow sensor. If readings are off, the engine may run roughly or stall. The fix is to inspect the sensor and replace it if needed.
Fuel system problems can also cause the engine to stumble or stall. Diagnostics check for leaks, fuel pressure, and injector operation to pinpoint the issue.
The warning may also appear if there is a fuel system leak or ignition timing fault that leads to engine damage over time. Addressing these issues promptly helps protect engine health.
In many cases multiple faults can trigger the warning, so a comprehensive diagnostic scan with an OBD-II tool is recommended to identify all contributing faults.
Regular maintenance, including using quality fuel, ensuring exhaust and sensor integrity, and periodic sensor checks can reduce the chance of warning lights appearing and keep engines running smoothly.