Table of contents: Removal ↓ Installation ↓
The oxygen content in the exhaust gases is measured by lambda sensors (oxygen sensors), which are used for precise control of the combustion of the fuel-air mixture. The composition of the mixture is regulated to achieve an excess air coefficient of l = 1. The toxicity reduction system using a lambda sensor ensures a reduction in the concentration of toxic components in the exhaust gases.
The lambda sensor is installed in the exhaust pipe before the catalytic converter. On 125 hp engines, the lambda sensor is installed in the exhaust manifold. On cars with six-cylinder engines, two lambda sensors are installed.
Removal
Disconnect the electrical connector of the lambda sensor; which is located on the engine compartment bulkhead. Remove the sensor wiring from the mounting brackets.
Place the vehicle over an inspection pit or on a lift.
Remove the lower engine compartment splash shield.
Unscrew the lambda sensor from the exhaust pipe. On cars with 1.8-I engines, you must use the VW-3337 key to unscrew the lambda sensor. If you do not have such a key, you must remove the exhaust pipe to access the lambda sensor.
Installation
Apply a thin layer of Audi 3337/9 grease to the threads of the lambda sensor. When installing a new oxygen sensor, its threads are already greased.
Screw the oxygen sensor into the exhaust pipe and tighten it to 50 Nm.
Connect the lambda sensor electrical connector and secure the sensor wiring with clamps. Make sure that there is no contact between the lambda sensor wiring and the exhaust pipe.
Install the lower engine compartment splash shield.
Lower the car to the ground.
(The original source of the article can be found on the website AUDImanual)