Which gauge response is expected after the engine is started?
Correct answer: B – The coolant temperature gradually rises toward its normal range
After startup, the coolant-temperature gauge should begin a gradual rise toward the normal operating range. Oil pressure should reach its normal range within seconds. On an air-brake vehicle, air pressure should also build at the rate specified for the vehicle rather than remaining low for an extended period.
Source: Nebraska Commercial Driver’s License Manual — § 2.1.5, “Look at the Gauges”

