On a cold New Jersey morning, plenty of people start the car, go back inside, and let it warm up. Most never realize that leaving a running vehicle unattended can be a traffic violation under N.J.S.A. 39:4-137. It’s a minor offense, but it surprises drivers — and there’s a persistent myth about winter that gets people ticketed. Here’s how the rule actually works, where it applies, and what to do if you’ve been cited.
What the law requires
N.J.S.A. 39:4-137 generally prohibits leaving a motor vehicle unattended on a highway or public area with the engine running, without taking reasonable steps to prevent it from moving or being taken — typically stopping the engine, setting the brake, and removing the key. The law’s purpose is safety and anti-theft: an unattended running car can roll, be stolen, or be taken with a child inside.
Read that list of precautions again, because it’s the whole statute in miniature: engine off, brake set, key out. The rule isn’t aimed at drivers sitting in an idling car — it’s aimed at the running car with nobody in it. Once you see the purpose (a driverless car that can roll away or drive away), the situations that draw tickets become predictable.
Where it applies — and where it’s murkier
The clearest application is on a public road or public area. Whether and how the rule reaches a private driveway is more nuanced — but cars left running in semi-public spaces like apartment lots, gas stations, and store lots are where these tickets most often arise. Many people first learn the rule exists only after the car is ticketed — or gone.
That public-versus-private line is not a technicality; it’s often the case. A summons written for a car idling in a genuinely private space raises a real question about whether the statute reaches that spot at all, and it’s one of the first things worth checking before you pay anything.
Who actually gets this ticket
The same handful of scenarios produce most 39:4-137 summonses:
- The winter warm-up — car running in front of an apartment building or on the street while the driver waits inside.
- The quick errand — engine left running outside a convenience store or coffee shop “for two minutes.”
- The gas-station idle — car running, driver inside paying or shopping.
- Deliveries and drop-offs — drivers who leave the engine running at every stop as a matter of routine.
None of these people think of themselves as committing a traffic offense — which is exactly why the ticket stings. Like an obstructed-windshield ticket, it punishes an everyday habit most drivers never knew was regulated.
Why a minor ticket can still matter
Standing alone, a 39:4-137 violation is a minor fine. The bigger consequences are usually indirect:
- Theft — an idling, unattended car is an easy target, and a stolen vehicle is a far bigger problem than the ticket.
- Insurance complications — leaving keys in a running car can affect a theft claim.
- It’s a moving-vehicle-related citation — worth handling correctly rather than ignoring, like any Title 39 ticket that can snowball if unaddressed into a bench warrant.
The stolen-car scenario deserves emphasis, because it’s where this small statute does its worst damage. If your warming-up car is taken, you’re now dealing with a police report, an insurance claim that may get hard questions about the keys being in the ignition, and whatever the thief did with the car afterward. The ticket is the cheapest part of that morning.
What happens after the ticket
A 39:4-137 summons follows the standard New Jersey municipal-court path: it can be paid, or it can be addressed in court. Paying is a guilty plea — the plea-by-mail reflex — and while this particular ticket is low-stakes on its own, the habit of paying every summons without a look is how drivers accumulate a record they didn’t need. Anyone carrying points already, or anyone whose record matters for work, should understand how New Jersey’s license point system turns “just pay it” decisions into long-tail insurance costs before adding anything else to the file.
How these tickets get handled
The statute has specific requirements, and each is a place where a cited driver can push back:
- Was the vehicle actually “unattended” in a public area as the statute requires? A passenger in the car, or the driver steps away, changes the picture.
- Were reasonable precautions taken — brake set, steps to prevent movement?
- The circumstances and location — public road versus private property, and whether the spot is one the statute reaches at all.
It’s generally a low-stakes ticket, but as with any summons, simply paying it without a look isn’t always the best move — especially if it arrived alongside other charges from the same encounter, the way a credentials check can surface a registration problem on top of the original stop.
A running-car ticket takes minutes to review
It’s a minor violation, but if you’ve been cited under 39:4-137 — or worse, your warming-up car was stolen — it’s worth a free call to handle it and understand the fallout. As New Jersey traffic ticket lawyers we can usually tell you in one conversation whether this is a pay-it, fight-it, or fix-the-bigger-problem situation. Call 908-692-7745 — the consultation is free, and our fees are flat, set by case type, and explained upfront.
Part of our complete guide: For every related New Jersey offense, claim, and defense in one place, see our NJ Traffic Ticket Defense Guide.