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 names for pre-catalyst and post-catalyst oxygen sensors are typically referred to as "upstream" (before the catalytic converter) and "downstream" (after the catalytic converter) sensors, respectively. The alphanumeric codes provided in option D do not correspond to standard naming conventions for these sensors.

All of the Following Statements Are True EXCEPT