What is the fault when the Peugeot 307 emission warning light comes on?

[SanJade]

Engine emission warning light comes on due to: 1. Poor fuel quality affecting the oxygen sensor damage or catalytic converter poisoning in the three-way catalytic system; 2. Fuel pump or ignition device malfunction; 3. Carbon deposits in the intake tract or piston top affecting poor atomization. The reasons for the car engine warning light coming on are: 1. Poor gasoline quality leading to incomplete combustion of the mixture in the cylinder, causing carbon deposits; 2. Excessive engine mileage, weakening the working characteristics of spark plugs; 3. Aging of vehicle machinery; 4. Damage, poor contact, or signal interruption of water temperature, crankshaft position, air flow, intake temperature, or oxygen sensors. The solutions for the car engine warning light coming on are: 1. Timely inspection of the car engine's condition; 2. Checking the condition of the car's sensors, air flow sensors, and spark plug components; 3. Checking for any engine knocking; 4. Checking for any faults in the ignition coil.