Colorado Car Idling Laws: It Turns On the Lock

Q: Which Colorado law actually covers this?

C.R.S. 42-4-1206, “Unattended motor vehicle - definitions.”, in the Colorado vehicle code. It is a theft provision rather than an environmental one, which is why a search for an idling law does not return it. The operative sentence is quoted on this page and links to the Colorado General Assembly Office of Legislative Legal Services page it was read from.

Q: Can you leave a car running in your own driveway in Colorado?

The Colorado section carries no scope sentence narrowing it to a road, so nothing in the statute distinguishes a driveway from a street. 20 states do carry one, and those are listed on the national page along with the sentence each of them uses.

Q: What does Colorado charge for it?

a class B traffic infraction, printed inside the section rather than left to a general penalty provision. Colorado is one of 18 states that print what it costs beside the rule rather than leaving it to a general penalty section further back in the chapter. The wording below is the statute's own.

Q: How current is this?

Every line was read on September 23, 2026, off the state's own published code, and links back to the section it came from. Legislatures amend these between sessions and a repeal leaves the old text in circulation for years afterwards, so the link beside each quote is what governs on the day.

Prohibited

Leaving it running unattended

C.R.S. 42-4-1206

It decides it

Whether the lock matters

one of 9 states written this way

No scope limit

How far the chapter reaches

20 states confine theirs to a road

None

Separate idling limit

only 16 states run one

September 23, 2026

Read

off the state’s own code

The short answer

In Colorado it turns on whether the car was left unlocked.

Colorado prohibits it only where the car was left unlocked or the key left in the ignition, which is the clause the whole question turns on. That single word is the whole answer and it is the word every national roundup drops: 9 states of the 34 that prohibit this at all build the offence around the car being unsecured, and Colorado is one of them. The section is quoted below in full so the clause can be read where it sits.

The Colorado chapter carries no scope provision narrowing this section to a road, unlike the 20 states whose chapters do.

If unlockedTurns on the lockC.R.S. 42-4-1206No separate idling limit

The section itself

C.R.S. 42-4-1206, and the sentence it turns on

This is a theft provision rather than an environmental one, which is why a search for a Colorado idling law does not return it and why so much of what is written about it is written about a different statute. It sits in the vehicle code with the rules about stopping and standing, and it was put there to stop cars being driven away by somebody who did not own them.

The operative sentence is reproduced below rather than summarised, because everything that separates one state from the next in this reading sits inside it. The card carries the citation, the title the code gives the section, and the link the sentence was read from.

C.R.S. 42-4-1206

If unlocked

Unattended motor vehicle - definitions.

(1) A person driving or in charge of an unlocked motor vehicle shall not permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, and effectively setting the brake thereon. When the vehicle is standing upon any grade, the person shall turn the front wheels to the curb or side of the highway in such a manner as to prevent the vehicle from rolling onto the traveled way.

The sentence that decides where it reaches

(2) The provisions of this article relating to the operation of vehicles and the movement of pedestrians refer exclusively to the use of streets and highways except: (a) Where a different place is specifically referred to in a given section; (b) For provisions of sections 42-2-128, 42-4-1301 to 42-4-1303, 42-4-1401, 42-4-1402, and 42-4-1413 and part 16 of this article which shall apply upon streets and highways and elsewhere throughout the state.

What the code says it costs

(2) Any person who violates any provision of this section commits a class B traffic infraction.

What it turns on Only where the car was left unlocked or the key left in it
Penalty a class B traffic infraction
Exemptions written in 3

Colorado Revised Statutes 2024, Title 42, Vehicles and Traffic, Colorado General Assembly Office of Legislative Legal Services, read September 23, 2026

The clause the answer turns on

In Colorado it depends on whether the car was left unsecured

The words that do it are in the section itself rather than in a note beside it, which is why a summary of Colorado law that says only "prohibited" is answering a different question than the one asked. Nine states are written this way.

A car left locked with the engine running is not what that sentence describes, and a car left unlocked with the key in it plainly is. The gap between those two readings is the difference between a page that answers the question and a page that repeats the word "prohibited" and stops. The other 8 states written the same way are below, each with its own sentence, because the wording is not the same from one to the next.

The 9 states whose section is built around an unsecured vehicle, read September 23, 2026.
State	Citation	The sentence, in the code’s own words
Colorado	C.R.S. 42-4-1206	(1) A person driving or in charge of an unlocked motor vehicle shall not permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, and effectively setting the brake thereon. When the vehicle is standing upon any grade, the person shall turn the front wheels to the curb or side of the highway in such a manner as to prevent the vehicle from rolling onto the traveled way.
Florida	Fla. Stat. § 316.1975	(1) A person driving or in charge of any motor vehicle may not permit it to stand unattended without first stopping the engine, locking the ignition, and removing the key.
Idaho	Idaho Code 49-602	No person driving or in charge of a motor vehicle shall permit it to stand unattended without first locking the vehicle if the engine is running, effectively setting the parking brake and, when standing upon any grade, turning the front wheels to the curb or side of the highway. The provisions of this section do not apply to motor vehicles on private property.
Illinois	625 ILCS 5/11-1401	Except for a law enforcement officer or an operator of an authorized emergency vehicle performing his or her official duties, no person driving or in charge of a motor vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, effectively setting the brake thereon and, when standing upon any perceptible grade, turning the front wheels to the curb or side of the highway.
Kansas	K.S.A. 8-1573	(a) No person driving or in charge of a motor vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, effectively setting the brake thereon and, when standing upon any grade, turning the front wheels to the curb or side of the highway.
Maryland	Md. Code Ann., Transp. 21-1101	(a) Except as provided in subsection (c) of this section, a person driving or otherwise in charge of a motor vehicle may not leave it unattended until the engine is stopped, the ignition locked, the key removed, and the brake effectively set.
New Hampshire	RSA 265:72	I. No person driving or in charge of a vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key, and effectively setting the brake thereon and, when standing upon any grade, turning the front wheels to the curb or side of the way, unless such vehicle has been started by remote control car starter. This paragraph does not prohibit a person in charge of a vehicle from idling the vehicle unattended on his or her own property.
Ohio	Ohio Rev. Code 4511.661	(A) No person driving or in charge of a motor vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, effectively setting the parking brake, and, when the motor vehicle is standing upon any grade, turning the front wheels to the curb or side of the highway.
Texas	Tex. Transp. Code Sec. 545.404	(a) Except as provided by Subsection (b), an operator may not leave a vehicle unattended without:(1) stopping the engine;(2) locking the ignition;(3) removing the key from the ignition;(4) setting the parking brake effectively; and(5) if standing on a grade, turning the front wheels to the curb or side of the highway.

Where the duty stops

The Colorado chapter carries no limit to a road

The Colorado chapter carries no scope provision narrowing this section to a road, unlike the 20 states whose chapters do.

A scope provision is where 20 of the fifty put the limit that a driveway question turns on, so its absence here is worth saying out loud rather than leaving a reader to assume one is there. Nothing in the chapter distinguishes a driveway from a street.

A two storey house behind a long concrete driveway with two cars parked up by the garage doors, a public footway crossing the foreground, and a thin dusting of snow over everything — Twenty of these sections sit in a chapter that reaches only a highway or a public way. The line those chapters turn on runs across the bottom of this frame, and it is nowhere in the section a reader would have found. “A dusting of snow on the front of a house and driveway along Aqueteong Lane, Ewing Township, Mercer County, New Jersey”, Famartin, CC BY-SA 4.0

What the rule lets through

The 3 exemptions written into the Colorado section

Three exemptions are written into the Colorado section, each quoted below from the sentence that creates it. An exemption narrows the rule it sits in, which makes it load bearing in exactly the way that rule is, so none of them is paraphrased.

a locked vehicle
(1) A person driving or in charge of an unlocked motor vehicle shall not permit it to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition, and effectively setting the brake thereon.
the sentence that creates it, read September 23, 2026
a remote starter system or adequate security measures
(3) The use or operation of a remote starter system or adequate security measures is sufficient to comply with subsection (1) of this section.
the sentence that creates it, read September 23, 2026
what counts as adequate security measures
(4) As used in this section: (a) "Adequate security measures" includes, but is not limited to: (I) Using a vehicle that requires a key to put the vehicle into gear and move the vehicle; (II) Keeping a keyless start fob out of proximity of the vehicle; or (III) Employing steering wheel security devices. (b) "Remote starter system" means a device installed in a motor vehicle that allows the engine of the vehicle to be started by remote or radio control.
the sentence that creates it, read September 23, 2026

What the code says it costs

Colorado prints the penalty beside the rule

Colorado is one of 18 states that print what it costs beside the rule rather than leaving it to a general penalty section further back in the chapter. The wording below is the statute's own.

It is quoted on the card above in the sentence it was read from. What a penalty clause says and what a court does with it are different questions, and only the first of them is on this page. Nationally 18 of the 34 states that prohibit this print a figure or a classification inside the section; the rest send a reader back to the general penalty provision for the chapter.

The other law entirely

Colorado runs no emissions idling limit

Colorado runs no separate emissions idling limit, so there is nothing behind the results a search for an idling law returns. Only 16 states run one at all, and most are written for buses and for trucks above a weight rather than for a car.

The two are kept apart on this page for the same reason they are apart in the books. An unattended vehicle section sits in the vehicle code and exists to stop a car being taken. An idling limit is an air quality regulation, written by an environmental agency, aimed mostly at buses and at trucks above a weight, and enforced by somebody else. Only 16 states publish one at all, and 2 of those name the regulation without putting a figure where a reader can reach it.

How Colorado compares

The same question in the other forty nine

34 states prohibit leaving a car running unattended and 16 have no section for it. Of the 34, 9 turn on whether the car was left unsecured, 20 sit in a chapter that reaches a road and nothing else, and 5 apply wherever the car is standing.

The bar splits the fifty by what their section does, and the table beneath it puts the strictest reading first, which is not the order a reader would guess from a map of how cold it gets.

5Always

9If unlocked

17Highways

3Public ways

16No section

Fifty state vehicle codes read September 23, 2026, strictest reading first.
State	What the section does	Citation	Turns on the lock	Separate idling limit
Kentucky	AlwaysProhibited wherever the car is standing	KRS 189.430	No	No
Louisiana	AlwaysProhibited wherever the car is standing	La. R.S. 32:145	No	No
Nevada	AlwaysProhibited wherever the car is standing	NRS 484B.530	No	No
Utah	AlwaysProhibited wherever the car is standing	Utah Code 41-6a-1403	No	No
Vermont	AlwaysProhibited wherever the car is standing	23 V.S.A. § 1111	No	Yes
Colorado	If unlockedOnly where the car was left unlocked or the key left in it	C.R.S. 42-4-1206	Yes	No
Florida	If unlockedOnly where the car was left unlocked or the key left in it	Fla. Stat. § 316.1975	Yes	No
Idaho	If unlockedOnly where the car was left unlocked or the key left in it	Idaho Code 49-602	Yes	No
Illinois	If unlockedOnly where the car was left unlocked or the key left in it	625 ILCS 5/11-1401	Yes	Yes
Kansas	If unlockedOnly where the car was left unlocked or the key left in it	K.S.A. 8-1573	Yes	No
Maryland	If unlockedOnly where the car was left unlocked or the key left in it	Md. Code Ann., Transp. 21-1101	Yes	Yes
New Hampshire	If unlockedOnly where the car was left unlocked or the key left in it	RSA 265:72	Yes	Yes
Ohio	If unlockedOnly where the car was left unlocked or the key left in it	Ohio Rev. Code 4511.661	Yes	No
Texas	If unlockedOnly where the car was left unlocked or the key left in it	Tex. Transp. Code Sec. 545.404	Yes	Yes
Alabama	HighwaysProhibited, but the chapter reaches highways only	Ala. Code Section 32-5A-50	No	No
Alaska	HighwaysProhibited, but the chapter reaches highways only	13 AAC 02.480	No	No
California	HighwaysProhibited, but the chapter reaches highways only	Cal. Veh. Code 22515	No	Yes
Delaware	HighwaysProhibited, but the chapter reaches highways only	21 Del. C. § 4182	No	Yes
Hawaii	HighwaysProhibited, but the chapter reaches highways only	HRS 291C-121	No	No
Michigan	HighwaysProhibited, but the chapter reaches highways only	Mich. Comp. Laws 257.676	No	No
Mississippi	HighwaysProhibited, but the chapter reaches highways only	Miss. Code Ann. 63-3-909	No	No
Nebraska	HighwaysProhibited, but the chapter reaches highways only	Neb. Rev. Stat. 60-6,168	No	No
New Jersey	HighwaysProhibited, but the chapter reaches highways only	N.J.S.A. 39:4-137	No	Yes
New Mexico	HighwaysProhibited, but the chapter reaches highways only	NMSA 1978, Section 66-7-353	No	No
New York	HighwaysProhibited, but the chapter reaches highways only	N.Y. Vehicle and Traffic Law § 1210	No	Yes
Oklahoma	HighwaysProhibited, but the chapter reaches highways only	47 O.S. 11-1101	No	No
Oregon	HighwaysProhibited, but the chapter reaches highways only	ORS 811.585	No	Yes
Pennsylvania	HighwaysProhibited, but the chapter reaches highways only	75 Pa.C.S. § 3701	No	Yes
South Carolina	HighwaysProhibited, but the chapter reaches highways only	S.C. Code Ann. SECTION 56-5-2570	No	No
Tennessee	HighwaysProhibited, but the chapter reaches highways only	Tenn. Code Ann. 55-8-162	No	No
Washington	HighwaysProhibited, but the chapter reaches highways only	RCW 46.61.600	No	No
Massachusetts	Public waysProhibited, but the statute reaches a public way only	M.G.L. c. 90, § 13	No	Yes
North Carolina	Public waysProhibited, but the statute reaches a public way only	N.C.G.S. § 20-163	No	No
Rhode Island	Public waysProhibited, but the statute reaches a public way only	R.I. Gen. Laws § 31-22-1	No	Yes
Arizona	No sectionNo unattended vehicle section in the code	No section	No	No
Arkansas	No sectionNo unattended vehicle section in the code	No section	No	No
Connecticut	No sectionNo unattended vehicle section in the code	No section	No	Yes
Georgia	No sectionNo unattended vehicle section in the code	No section	No	No
Indiana	No sectionNo unattended vehicle section in the code	No section	No	No
Iowa	No sectionNo unattended vehicle section in the code	Iowa Code 321.362	No	No
Maine	No sectionNo unattended vehicle section in the code	No section	No	Yes
Minnesota	No sectionNo unattended vehicle section in the code	No section	No	No
Missouri	No sectionNo unattended vehicle section in the code	No section	No	No
Montana	No sectionNo unattended vehicle section in the code	Mont. Code Ann. 61-8-357	No	No
North Dakota	No sectionNo unattended vehicle section in the code	No section	No	No
South Dakota	No sectionNo unattended vehicle section in the code	SDCL 32-30-5	No	No
Virginia	No sectionNo unattended vehicle section in the code	No section	No	Yes
West Virginia	No sectionNo unattended vehicle section in the code	No section	No	No
Wisconsin	No sectionNo unattended vehicle section in the code	No section	No	No
Wyoming	No sectionNo unattended vehicle section in the code	W.S. 31-5-509	No	No

Colorado car idling questions

Is it illegal to leave your car running unattended in Colorado?

Colorado prohibits it only where the car was left unlocked or the key left in the ignition, which is the clause the whole question turns on. That single word is the whole answer and it is the word every national roundup drops: 9 states of the 34 that prohibit this at all build the offence around the car being unsecured, and Colorado is one of them. The section is quoted below in full so the clause can be read where it sits. The Colorado chapter carries no scope provision narrowing this section to a road, unlike the 20 states whose chapters do.

Which Colorado law actually covers this?

Does it matter whether the car was locked in Colorado?

Yes, and it is the only thing that matters. The Colorado section is written around an unsecured vehicle, so a car left locked with the engine running is not what the sentence describes. The words that do it are in the section itself rather than in a note beside it, which is why a summary of Colorado law that says only "prohibited" is answering a different question than the one asked. Nine states are written this way. The full sentence is on this page.

Can you leave a car running in your own driveway in Colorado?

What does Colorado charge for it?

Does Colorado have an idling limit?

How current is this?

Car idling laws in every state

Colorado studded tire lawThe other winter driving rule a state writes and a city can change, with the dates each one sets.Colorado sidewalk snow rulesHow long a city gives before the walk has to be clear, quoted from the ordinance that sets it.Colorado frozen pipesWhat the same cold morning is doing to the building the car is parked beside.Colorado first snowWhen the mornings that raise this question usually start, measured against the years behind it.

Colorado read September 23, 2026, off the state’s own published code: C.R.S. 42-4-1206 and the chapter it sits in. Every quotation above is reproduced in the source’s own wording and links back to the document it was read from. Legislatures amend these between sessions and a repealed section stays in circulation for years afterwards, so the link beside a quote is what governs on the day. What Colorado wrote is what this page carries: the offence, the clause it turns on, how far the chapter reaches, what the legislature exempted, and the sentence it set.