Carbon monoxide — Missouri Permit Test

Carbon monoxide on the Missouri permit test — 4 rules, each with the reason behind it and a question on it while it is fresh.

The rules

Vehicle motors give off carbon monoxide, which is a deadly gas.

It has no smell and no color, so the first warning is usually feeling unwell, which is already too late.

Vehicle motors give off carbon monoxide which is a deadly gas.
Missouri Driver Guide, p.59

Do not leave the motor running in a garage.

A closed garage fills with exhaust faster than most people expect, and there is no warning.

Do not leave the motor running in a garage.
Missouri Driver Guide, p.59

Do not leave the vents open when following closely behind another vehicle.

The exhaust from the car in front comes straight into your cabin through the vents.

Do not leave the vents open when following closely behind another vehicle.
Missouri Driver Guide, p.59

Do not drive with a defective muffler or exhaust system.

A leaking exhaust puts the gas under the floor of your own car, where it finds a way in.

Do not drive with a defective muffler or exhaust system.
Missouri Driver Guide, p.59

On the test

What does the guide say about carbon monoxide from a vehicle motor?

It is a deadly gas. It has no smell and no color, so the first warning is usually feeling unwell, which is already too late. Missouri Driver Guide, p.59: “Vehicle motors give off carbon monoxide which is a deadly gas.”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

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Where these come from

Every rule here is checked against Missouri Driver Guide, published by the Missouri Department of Revenue, and against the state code itself. Last checked 2026-09-16.