Lambda Sensor, also known as gas concentration sensor, is an essential sensor in the engine electronic control system. Its function is to obtain the air-fuel ratio signal of the gas mixture by monitoring the content of oxygen ions in the exhaust, and then convert the air-fuel ratio signal into an electronic signal for the engine ECU. The ECU adjusts the injection time based on the signal of Lambda Sensor to achieve the feedback (closed-loop) control of air-fuel ratio. The air-fuel ratio is controlled at around 14.7 (the excess air coefficient is 0.98 ~ 1.02), so that the engine can get the best concentration of gas mixture in order to reduce harmful gas emissions and save fuel.undefined

Primary failure mode

The failures of the Lambda Sensor are mainly caused by signal problems due to heavy metal poisoning, circuit failure, chip fracture, loose sealing, air leakage, etc.

● Heavy metal poisoning is mainly caused by fuel oil or due to service life.

● Circuit failure is mainly due to the strength of welding, as well as open circuit and short circuit in installation and use.

● The main causes of chip fracture include materials used by the manufacturer, the production process and transportation.

● Air leakage caused by sealing problem needs to be controlled at the assembly line, including material, process, inspection and so on.

At present, most of the manufacturers have mature technology and sufficient experience in tubular Lambda Sensor. More attention should be focused on new type of Lambda Sensors such as chip type.

By Andy RS ZHANG

keywords：Intake System Exhaust Sensor Urea Pump System Catalyst & Encapsulation