The lambda sensor, or what is commonly referred to as an oxygen sensor, measures the amount of air in the exhaust stream. It transmits this information to the engine control unit to analyse and modify how much fuel enters the engine. If the amount of air is minimal it restricts fuel flow; if air flow is high, the fuel injectors remain open for a longer period of time. The sensor is very sensitive to soot and heat; as a result, it can fail over the course of thousands of miles of use. If the oxygen sensor in your Alfa Romeo is bad, replace it immediately so that your engine runs smoothly and efficiently.
Open the bonnet and prop it up.
Unplug the oxygen sensor at the connector by pushing down on the tab and pulling outward.
Place a spark plug socket on your ratchet. Slip it over the oxygen sensor and loosen.
Remove the oxygen sensor and thread in the new one. Tighten it with a ratchet.
Reconnect the electrical connector by pushing it into the other electrical connector.
Before threading the oxygen sensor back into the exhaust manifold, place anti-seize onto the threads to facilitate removal of the oxygen sensor.
Wear safety glasses when working on your Alfa Romeo.