Carbon monoxide — Texas Permit Test

Carbon monoxide on the Texas permit test — 5 rules, each with the reason behind it and a question on it while it is fresh.

The rules

Cars produce carbon monoxide, which is a deadly gas, so a driver should make sure they are getting plenty of fresh air.

It has no smell and no taste, so nothing warns the person breathing it. Fresh air is the only defense.

Beware of carbon monoxide poisoning. Cars produce carbon monoxide, which is a deadly gas

Texas Driver Handbook, p.68

A driver should not leave the motor running in a garage.

A closed garage fills in minutes with a gas nobody can detect. It is the commonest way people are poisoned by a car.

Don’t: 1. Leave the motor running in a garage

Texas Driver Handbook, p.68

A driver should not leave the vents open when following closely behind another car.

The exhaust of the car ahead goes straight into your cabin. Closing the vents is the simplest fix.

Don’t: 1. Leave the motor running in a garage 2. Leave vents open when following closely behind another car

Texas Driver Handbook, p.68

A driver should not drive with a defective muffler or exhaust system.

A leaking exhaust puts the gas under the floor of the car. It is a mechanical fault that turns into a medical one.

Don’t: 1. Leave the motor running in a garage 2. Leave vents open when following closely behind another car 3. Leave the motor running and the windows closed while the car is parked 4. Drive with a defective muffler or exhaust system

Texas Driver Handbook, p.68

A person who finds a carbon monoxide poisoning victim should move them to fresh air and call 911.

Getting them out of the gas comes before anything else. Nothing can be done while they are still breathing it.

Don’t: 1. Leave the motor running in a garage 2. Leave vents open when following closely behind another car 3. Leave the motor running and the windows closed while the car is parked 4. Drive with a defective muffler or exhaust system 5. Use the heater or air conditioner in a parked car with the windows closed in an enclosed space If you encounter a carbon monoxide poisoning victim, move them to fresh air and call 911

Texas Driver Handbook, p.68

On the test

What does Texas say about carbon monoxide from a car?

It is a deadly gas that cars produce. It has no smell and no taste, so nothing warns the person breathing it. Fresh air is the only defense. Texas Driver Handbook, p.68: “Beware of carbon monoxide poisoning. Cars produce carbon monoxide, which is a deadly gas”

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Where these come from

Every rule here is checked against Texas Driver Handbook, published by the Texas Department of Public Safety, and against the state code itself. Last checked 2026-09-16.