Technician A says that the oxygen sensor provides the major input during the open-loop mode. Technician B says that the coolant temperature sensor input is not used during open-loop mode operation. Who is correct? a. Technician A
b. Technician B
c. Both A and B
d. Neither A nor B

The correct technician is;

b. Technician B

Explanation:

The closed-loop and open-loop refer to the mode of operation of engines that are fuel-injected based on whether the engine operates based on a feedback signal from an air/fuel ratio sensor which is also known as an oxygen sensor or a lambda so as to regulate the air fuel mixture which is the closed-loop, or whether the engine does not make use of the sensor input for its operation, which is the open-loop mode

Therefore, technician B that says the input of the coolant temperature sensor is not used during the open-loop is more correct as the engine does not make use of a sensor input during open-loop mode, the engine only operates based on the throttle's position.