I forgot the lights on overnight on a 2016 Volkswagen Jetta and 16 hours later when I came back to the car the lights were still on but the car wouldn't start.

Can't the car check the battery level and automatically turn off lights if it had been stopped for a long while so as to prevent the battery from completely draining out?

As in, always keep a reserve charge enough to start the engine.

UPDATE two weeks later after reading all the answers: it makes sense to allow the user to leave the lights on even with they key out of ignition (e.g. setting camp, or locking the car while going to get help). But I can't think of any situation in which it would make sense for a car to let the lights consume so much battery power (presumably 8+ hours of continuous lighting) that the car will no longer start. Even if there were some such strange situation (watching snails drunk on molasses setting up camp during the arctic night), if lights go off automatically every, say, 6 hours without the key in ignition, I doubt any car owner would have a problem with turning them back on, but far more owners will be grateful they didn't have their morning plans ruined because they had to jump start the car after humanly forgetting to turn off the lights or not hearing the car beep for whatever reason.

Perhaps car makers have something to learn about battery management from smartphone makers.

  • 3
    The constant state checking would also drain your battery. Not as much as leaving the lights on but probably enough depending on your reserve capacity to drain the battery overnight.
    – Ben
    Dec 22, 2016 at 22:49
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    Does the 2016 Jetta have an "auto" light switch and does that turn them off? I've seen a few cars with on/auto/off, where auto turns on in the dark and shuts off with the car or in daylight, but on is just always on.
    – Jason C
    Dec 22, 2016 at 23:10
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    Actually I suspect that the checking could be implemented in a manner that would useless power than the clock. Adding a feature like that wouldn't be an issue for cars that are driven on a "normal" schedule.
    – dlu
    Dec 22, 2016 at 23:11
  • 2
    (And so the common approach of just having a timer is probably simpler.)
    – Jason C
    Dec 22, 2016 at 23:20
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    Some cars do shut your lights off automatically, so they obviously can! For example, the modern Camaro, if running in automatic lights mode, will shut off your headlights several seconds after you shut it off. And since lights are automatic, ypu don't have to remember to turn them on, the next night. It will also shut off your dome light if the car is off for a long enough period of time.
    – atk
    Dec 23, 2016 at 3:24

9 Answers 9


All of these other answers go into weird philosophical directions...

The answer is much simpler than that:

Yes, it is possible to have the car turn off the headlights when the car turns off - many cars have an "Auto" setting for the headlights, and it does just this. They usually have a manual mode too, for those cases where you want the headlights on but the car is off.

Your car simply does not have this option. It was either an upgrade you did not purchase, or it's something VW decided not to offer on your car model. After all, the electronics to make automated lights costs money, and someone needs to pay for that.

Long story short, yes it's possible, just not with the factory options your particular car has installed.

  • 2
    Finally an answer that doesn't wander off into opinion territory. Btw I found some aftermarket auto headlight switch that apparently fits the 2016 Jetta.
    – Jason C
    Dec 23, 2016 at 17:57
  • How long do the headlights stay on in that "Auto" mode after the key has been removed from ignition? Jan 8, 2017 at 10:16
  • @DanDascalescu That depends on the car and it's settings. Some cars have configurable timers, others just a fixed timer. Usually they are about a minute or longer - enough time to get out of the car, grab a bag or something, and walk away before the headlights go off leaving you in the dark.
    – SnakeDoc
    Jan 9, 2017 at 15:42

This is another of those questions that can only be answered by a few people at VW, clearly the car could turn the headlights off after it is stopped; or after it is stopped and a certain amount of time has elapsed; or, as you suggest, by monitoring the battery and not allowing the battery to drain past the point where the car is likely to be able to start again.

The general answer to questions like this is that there are competing interests. For example:

  • Making the car "idiot proof" and designing it to do what, as best the designer can tell, is the "right" thing in a particular situation. That would be easy in this case. Power to the headlights could be controlled by the load reduction relay and they would go off when the car is turned off.

  • Deciding that most people are "not idiots" and letting them decide what how to use the car – for example allow turning on the headlights when the car is off as a source of light, perhaps while setting up camp or helping someone change a tire.

  • Making the car "smart" and building a circuit that would try to balance the first two options. That's easily enough done, but it would add some cost and complexity to the car and there would also be an "opportunity cost" – why this feature rather than some other one. There might also be a philosophy question, especially if you have a strong assumption that people are "not idiots" – how is the car to know when it is better to keep the lights on and run the battery dead and when it is better to preserve starting power. Usually it will be the latter by not always, so now you have to add an override and teach users how to use it (or prompt them to make a decision).

The bottom line is that decisions like this are harder than you think and for a product that will sell 10s of thousands or maybe even millions of copies the choice that seems obvious to me or you may really just be the preference of an outlier. Further what's "right" in one market maybe completely "wrong" or even illegal in another.

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    +1 for the last paragraph. In some regions, there are even rules for when you have to leave lights on in parked cars.
    – AndrejaKo
    Dec 23, 2016 at 2:02
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    @AndrejaKo, I couldn't believe what you said about parked vehicles, but it is true: when parking along the side of a road. A misguided rule, IMO. There's a signal designed specifically for illuminating a car in a potentially dangerous situation - conveniently called: the hazard lights.
    – predi
    Dec 23, 2016 at 8:16
  • @predi, Hazards are bright, and at least according to some research attract distracted drivers (that's why the German's don't allow flashing tail lights on bikes). The "parking lights" that I'm familiar with are one side only – perhaps to reduce battery drain. But the car maker doesn't get to argue with the rule, they have to comply (even if they are also working to change it).
    – dlu
    Dec 23, 2016 at 8:20
  • 1
    @dlu, the specific rule I found was for Colorado and it applies to headlights, not parking lights. The latter may be way more distracting for front-approaching traffic, especially if the car is in a specific elevated position. The hazard lights are meant to attract attention.
    – predi
    Dec 23, 2016 at 8:24
  • @predi, Good thing I don't park in Colorado… I think the problem the Germans have with flashing lights (at least the routine use of flashing lights like on bikes) is that they think – or maybe even have data to back it up – that they result in more accidents, distracted drivers follow the lights and end up hitting the source.
    – dlu
    Dec 23, 2016 at 8:27


  • sometimes, you need your headlights on even though the engine is off
  • cars with "smart" systems like this are annoying if you i) don't know how to operate/disable the "smart" system or ii) the "smart" system is interfering with what YOU are trying to do.
  • "smart" systems are expensive to engineer and need extra components/sensors, all this adds to the vehicle's sticker price. Cars are never designed to be "the best car ever," they are always designed with a price in mind.
  • one more thing that can break. Imagine if the sensor for the "smart" system is incorrectly reading the battery's voltage (because of corroded battery terminals) and decides to disable some electrical systems for the battery's sake?

All this just in case you forget your lights on? There's a chime that will tell you your lights are on and the engine is off. This has saved me on a handful of occasions, but I do reckon that it isn't fool proof. Between the 2 people I live with, they left the lights on 5 times in the past year, leading to 2 batteries getting replaced, 2 jumps, and the last time I happened to be outside and noticed the lights on. I'd rather yell at them than have to pay for and deal with "smart" systems.

  • I agree with your vision, but the "yell at them" bit isn't really a good idea. Maybe "punish" them or something? (Make them pay for the battery or teach them how to deal with the jump start (is that the right name?) may be more effective). This is just my opinion. Dec 23, 2016 at 11:06
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    Smart systems being annoying is an opinion unless you're citing user testing results. Engineering cost is unknown and could just as easily be negligible, we do not know for the Jetta, unless you can cite VW engineering cost research documents. Fail-safes are conceivable and can be evolved over time to be reliable as with every other system on a vehicle, although e.g. lawsuits against failures of similar past systems could suggest otherwise if you know of any. This all seems to be conjecture. Can you improve any of this with references?
    – Jason C
    Dec 23, 2016 at 15:18
  • My 2001 Elantra would shut off the headlights as soon as the car turned off (it didn't have an auto-light feature). Turning them on while the car was off was as simple as switching them to the off position and turning them back on. Dec 23, 2016 at 16:25
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    My car has several headlight settings: "off", "sidelights", "headlights" and "auto" which turns them on when needed and makes sure they're off when I'm gone. It's great. And ten years old. Also, I love your username. Dec 23, 2016 at 19:44

For what it's worth, my Subaru has what I think is the perfect solution -- headlights and parking lights turn off when you turn off the ignition switch. You can keep the headlights on all the time while you're driving and never worry that you'll forget to turn them off when you park.

If you really want the parking lights to stay on, there's a separate switch on top of the steering column for that (but in 10 years of owning the car, I've never needed it).

There's no way to keep the headlights on without having the ignition switch turned on, but I haven't found a use for that either.

  • 1
    IIRC, the Subaru Forester 2013 that my parents own works as you describe, but you can get the lights on with the car off just by turning the headlights on after turning the car off. (IDK how long they stay on in this case, though. But if it's indefinitely, then you can just switch the normal control off then on again after removing the keys.) Agreed that this seems like the ideal balance of foolproof and flexible. You can even just leave the lights in the on position on purpose, so they'll be on for the next drive. Dec 23, 2016 at 8:08
  • My Renault Megane III 2010 keeps the headlights on even after ignition is switched off. It turns them off after a certain timeout or after I open he front (driver's) door, whichever comes first. My car key has a button that allows me to turn the headlights on at any time remotely (except when the key is in its key slot, since this prevents physical access to the button) - they switch off after a timeout. Simple and effective.
    – predi
    Dec 23, 2016 at 8:15
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    Unfortunately, this does not seem to explain why some other vehicles do not also have this feature.
    – Jason C
    Dec 23, 2016 at 15:20
  • FIAT group vehicles (at least in the uk) have a small tab as part of the ignition switch that if depressed will keep the lights on when you remove the key, normal operation is to switch off lights when the key is removed
    – Mauro
    Aug 18, 2021 at 20:58

It is about the complexity of the product. dlu has many good points like only the person that actually made the design decision may give the right answer. But it is probably not exactly about the opportunity cost. It is most likely a design policy of VW to not micro manage these cases.

  • The feature has some connections with other features
  • Change in a feature can effect the other features
  • Adding complexity adds costs exponentially
  • There is a higher risk of bugs
  • There is also a risk of an illegal feature, the cars are audited for every market, so a simple design makes it faster
  • Some safety critical applications have some coding requirement like that every line of code must be commented and such. Thus in a safety critical application these effect are even worse.

In your car you have things you really want to be fool-proof like brakes and steering. Any small feature that may make the car a bit more fool-proof but adds even a small change of messing with those critical things. tlhIngan introduced some errors that the system can do. What if those happened while driving, because some safety check was not implemented or if there was a bug somewhere else that led to the system think that the car is in safe. If the driving lights would be turned off in a non-lighted curve, it would be quite scary.

It is easy to see why VW might have a policy of not micro-managing features for some fairly rare scenarios, that do not introduce significant risk for the safety.

  • While these are reasonable considerations, I argue that such a system would likely evolve to be reliable over time, if there was consumer demand for it. It would also likely be heavily tested during development and come out at least reasonably safe. On one hand it could evolve just as every other complex system on your vehicle evolved, on the other hand sure it could end in a massive recall, but that doesn't set it apart from other systems. Point being, "not worth the risk" isn't hugely compelling, and we also do not know if this is why, unless you have vw internal design memos to cite.
    – Jason C
    Dec 23, 2016 at 15:25
  • @JasonC the safety critical applications may have regulations that it must be almost mathematically proven that there is no bugs, or at least it must be proven that every possible counteraction is taken, like commenting code by explaining every action of the code. Even if you would exclusively distribute the systems in a fool-proof way that the car will not utilize the automatic controls to lights unless the car is stationary, there could be use scenarios like an accident on a dark road. There it could be that the head light is the ultimate savior of lives. Dec 27, 2016 at 12:32
  • Also I have never heard about software updates for a car. Without possibility to distribute the updates via WWW, all the cars would need to be taken to the dealership. Dec 27, 2016 at 12:32
  • @user3644640: Tesla vehicles regularly receive over-the-air updates. Jan 8, 2017 at 10:13

In many VAG cars, the lights stay on when you switch off the engine. Then a buzzer goes off when you open the door, to remind you to switch off the lights.

Since about 2008, with the addition of daytime running lights, the DRL are switched off automatically. The main/dipped headlights aren't though.


Actually, I just realized we're all overthinking it.

There's 2 types of battery power sources on all vehicles:

  • always powered (think of your 4-way blinkers)
  • "key on" power (think of your radio and clock, you need to turn the key to use them)

Some items, like the cigarette lighter and auxiliary power outlets, vary from manufacturer to manufacturer on whether they are always powered or only powered when the key is on. Case in point, I own 4 vehicles and 2 of them have the cigarette lighter always powered and 2 of them have it on "key on" power.

Other items are more consistent among manufacturers, like headlights and 4-way blinkers. These are both always powered because you could need them without having the key: 4-way blinkers in case you break down and need to leave your vehicle on the side of the road (you take your key with you), headlights/parking lights for a variety of reasons (maybe you're lost or broken down on an unlit rural highway in the middle of the night and need lots of light to look at a map/repair instructions/tools). This is a design decision that's been thought out.

So there you have it: if you want your headlights and parking lights to be off when the key is removed, rewire them to "key on" power like your radio. No sensors, no finicky smart systems.


I have owned/driven several makes of cars over the past 40 years.. my 2014 VW Tiguan is the ONLY one that requires manual turnoff of headlights the CAA rep who came to jump-start it laughed as he asked "First time VW owner?" PUT IN A SENSOR - feel free to remove the tire pressure. one that rarely works


My 2012 Volkswagen Golf has automatic headlights which are connected to a sensor on the windscreen and turn on automatically when needed. Removing the key from the ignition switches them to a mode where they switch off within sixty seconds.

The cars headlight switch also features the traditional positions of off, sidelights and dipped headlights. When in the off position, the car displays daytime running lights when it's ignition is on. If left in the sidelight or dipped headlight position, the car will continue to display sidelights with the key removed until the battery finally runs out.

As Microsoft are so fond of saying "This behaviour is by design." If you don't want your cars headlights to remain on for sixteen hours after being parked, place the headlight switch in the Off (or, if fitted, Auto) position.

  • Unfortunately, this does not seem to explain why some other vehicles do not also have this feature.
    – Jason C
    Dec 23, 2016 at 15:26
  • I don't understand the question. Surely it should be why do some cars have auto off lights. Which is an option on the higher spec VWs. Dec 23, 2016 at 18:50
  • It is not a very good question for this Q&A site.
    – Jason C
    Dec 23, 2016 at 18:59

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