In the described scenario, if a parked truck’s speedometer shows a value greater than zero, what is the likely condition?

• A. The gauge is defective
• B. The fuel gauge is low
• C. The engine is running
• D. The parking brake is engaged

Answer: (A)

When a vehicle is parked, the speedometer should read zero because speed is zero when there’s no movement. If it shows a value above zero while parked, the reading isn’t due to actual motion but a fault in the speed-reading system.

The speedometer gets its signal from the wheel speed sensor or transmission and converts that into a display. If that signal is faulty, or if the gauge needle is stuck, you can see a nonzero reading even though the truck isn’t moving. The other factors listed—fuel level, whether the engine is running, or whether the parking brake is engaged—do not by themselves cause a speed reading to be higher than zero when the vehicle is stationary, so they don’t explain this situation. The most plausible explanation is that the gauge itself is defective.