1. Oxygen sensor issues: The oxygen sensor monitors the amount of oxygen in the exhaust gas and helps control the air-fuel mixture. When the oxygen sensor is faulty, it can cause a lean or rich mixture, resulting in the check engine light illuminating.
2. Catalytic converter issues: The catalytic converter helps reduce harmful emissions by converting pollutants into less harmful gases. If it is damaged or malfunctioning, it can cause the check engine light to come on.
3. Ignition system problems: Faulty spark plugs, ignition coils, or high-tension wires can cause misfires, leading to the check engine light.
4. Fuel injector issues: If the fuel injectors are clogged or faulty, they may not deliver the correct amount of fuel to the engine, resulting in the check engine light coming on.
5. EVAP system problems: The EVAP system is responsible for controlling emissions from the fuel system. If there are any issues with the EVAP system, it can trigger the check engine light.
6. Faulty engine sensors: Various sensors in the engine monitor different parameters such as air temperature, engine coolant temperature, and engine speed. If any of these sensors fail, the check engine light may come on.
It's important to note that there can be other specific reasons for the check engine light to come on in a 2001 Toyota Echo, so if the light is illuminated, it's best to have a professional mechanic diagnose the exact cause and address the issue promptly to avoid potential further complications.
