A：First of all, let's see what part does the lambda sensor play in the vehicle. In engine using three way catalytic converter to reduce the exhaust emission, the lambda sensor is an essential element. Lambda sensor inside the exhaust pipe is used to detect the oxygen concentration and feed it back to the electrojet system ECU, then ECU controls the oil injection amount to control favorable air fuel ratio. Spoil of the lambda sensor may increase the oil consumption and exhaust emission and result in unstable idle and misfire of the engine.