All of the following statements are true EXCEPT: A) the fuel system monitor operates continuously when the fuel system is in closed loop. B) the heated oxygen sensor monitor (HO₂S) changes the injector pulse width while it checks the upstream O₂ sensor to see that its oscillating frequency is fast enough. C) O₂ sensors are monitored even before closed loop. D) a pre-catalyst sensor is called S₀ and a post-cat sensor is called sensor 1 (S₁).

Question

Quizplus · Accepted Answer

The correct answer is D because the naming convention provided for the pre-catalyst and post-catalyst sensors does not follow any standard automotive nomenclature for oxygen sensors or any other sensors. Typically, oxygen sensors are referred to as upstream (before the catalytic converter) or downstream (after the catalytic converter), and their designations are simpler, such as O2 Sensor Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream), without the complex alphanumeric codes provided in the options.

All of the Following Statements Are True EXCEPT