Understanding Engine Performance Sensors

What is the primary function of an oxygen sensor in an automotive engine?

• To measure engine oil pressure

• To monitor the amount of oxygen in the exhaust gases

• To control the throttle position

• To regulate coolant temperature

Which sensor is responsible for measuring the amount of air entering the engine?

• Knock sensor

• Mass airflow sensor

• Throttle position sensor

• Engine coolant temperature sensor

The throttle position sensor provides information to the engine control unit (ECU) about:

• The temperature of the engine coolant

• The position of the accelerator pedal

• The amount of fuel in the tank

• The position of the throttle valve

Which sensor helps the engine control unit (ECU) adjust the air-fuel mixture based on engine temperature?

• Oxygen sensor

• Knock sensor

• Engine coolant temperature sensor

• Mass airflow sensor

What is the main purpose of a knock sensor in an automotive engine?

• To detect abnormal combustion (knocking) in the engine

• To measure the amount of air entering the engine

• To monitor exhaust gas temperature

• To control the fuel injectors

A vehicle is experiencing poor fuel economy and increased emissions. Which sensor malfunction could most likely cause this issue, and why?

• Mass airflow sensor, because it measures the air entering the engine and helps determine the correct fuel amount

• Knock sensor, because it detects engine vibrations

• Throttle position sensor, because it controls the radiator fan

• Engine coolant temperature sensor, because it measures oil pressure

If the engine coolant temperature sensor sends a false low-temperature reading to the ECU, what is a likely consequence for engine operation?

• The engine will run lean

• The engine will run rich

• The throttle will close completely

• The oxygen sensor will stop working

A technician is diagnosing an engine with frequent knocking. Which sensor should be checked first, and what is its role in preventing engine damage?

• Oxygen sensor; it controls the air-fuel ratio

• Knock sensor; it detects engine knock and signals the ECU to adjust ignition timing

• Mass airflow sensor; it measures intake air

• Throttle position sensor; it controls idle speed

A car’s engine control unit (ECU) receives a signal indicating a wide-open throttle from the throttle position sensor, but the mass airflow sensor reports low airflow. What could be a possible reason for this discrepancy?

• The oxygen sensor is faulty

• There is a blockage in the air intake system

• The engine coolant temperature sensor is overheating

• The knock sensor is malfunctioning

A vehicle fails an emissions test due to high levels of unburned hydrocarbons in the exhaust. After checking, the oxygen sensor is found to be faulty. Explain how a malfunctioning oxygen sensor could lead to this result.

• The faulty oxygen sensor causes the ECU to supply too much fuel, resulting in incomplete combustion and higher unburned hydrocarbons

• The faulty oxygen sensor increases engine temperature, burning more hydrocarbons

• The faulty oxygen sensor causes the throttle to remain closed, trapping hydrocarbons

• The faulty oxygen sensor increases air intake, diluting hydrocarbons