Exhaust gas Oxygen (O2) Lambda sensor for all models of Porsche Boxster, 2.7L and Boxster S (3.2L) built 2003-2004 {Technical} The exhaust gas oxygen sensor (often refered to as the Lambda sensor or O2 sensor) is located in the Porsche Boxster exhaust system before and after the catalyst. There are a total of four sensors on each 986 Boxster. (1 before and 1 after the catalyst on the bank 1 exhaust system for cylinders 1-3, and 1 before and 1 after the catalyst on the bank 2 exhaust system for cylinders 4-6). All four of these O2 sensors are identical and fully interchangeable. The sensor's job is to detect the levels of uncombusted oxygen in the exhaust system before and after the catalyst. The information it collects is then passed back the engine control unit and appropriate fuellling and spark timing adjustments are made so that the engine always operates under optimum emissions conditions. A faulty or malfunctioning sensor will result in any or all of the following vehicle symptoms:- - Excessive fuel consumption - Driveability problems, such as engine surging, hesitation or lack of power (these symptoms can also be caused by a failed air flow sensor) - High hydrocarbon emissions, failing an emissions inspection - The engine warning lamp will be illuminiated - Emissions related fault codes stored in the engine control unit - Permanent damage to the catalytic converter
