Vehicle Operation & Maintenance Flashcards

What does the 'check engine' light indicate?

Answer: The vehicle's OBD system has detected a fault code

The check engine light signals that the vehicle's on-board diagnostics (OBD) system has detected a fault; a scan tool is needed to read the specific trouble code.

How does driving with an underinflated tire affect vehicle performance?

Answer: Increases fuel consumption, causes uneven wear, and reduces handling

Underinflated tires increase rolling resistance (hurting fuel economy), cause premature tread wear on the outer edges, and reduce steering response and handling precision.

What is the role of brake fluid in a vehicle's braking system?

Answer: It transfers hydraulic pressure from the pedal to the brake calipers

Brake fluid transmits the force from your foot on the pedal through hydraulic pressure to the brake calipers or wheel cylinders to slow the vehicle.

What does 'engine knocking' typically indicate?

Answer: Pre-ignition or detonation, often from low-octane fuel or carbon buildup

Engine knocking is caused by pre-ignition or detonation — the fuel-air mixture igniting too early or unevenly — often due to low-octane fuel or carbon deposits.

When should you replace your vehicle's spark plugs?

Answer: According to manufacturer schedule, typically 30,000–100,000 miles depending on plug type

Copper spark plugs last about 30,000 miles, while platinum or iridium plugs can last 60,000–100,000 miles; always follow the manufacturer's maintenance schedule.

What is the purpose of the exhaust gas recirculation (EGR) valve?

Answer: Reduces NOx emissions by recirculating exhaust gas into the intake

The EGR valve recirculates a portion of exhaust gas back into the engine's intake to lower combustion temperature, reducing nitrogen oxide (NOx) emissions.

What precaution should you take before jump-starting another vehicle?

Answer: Connect cables in order: positive to dead battery, positive to good battery, negative to good battery, negative to unpainted metal on dead car

The correct sequence (dead positive → good positive → good negative → unpainted metal on dead car) minimizes the risk of sparks near the battery, which can produce explosive hydrogen gas.