Do Fog Lights Come On Automatically? Auto Fog Lights Explained
Short answer: on most cars, fog lights don’t come on automatically. You press a button, and they stay on until you switch them off. Some cars have features that look similar, such as an “Auto” headlight setting, fog lights that double as cornering lights, or fog lights that light up when you reverse. Check your owner’s manual to see what your car does, and always switch fog lights off yourself when the fog clears.
“Auto fog lights” can mean two things: fog lights for cars in general, or fog lights that switch on by themselves. This guide covers both.
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Do fog lights come on automatically?
Usually not. A fog light is an addition to your headlights that you switch on when you need it. The reason is simple: fog lights are only for dense fog or falling snow, when you can’t see more than about 100 metres, so the car can’t just assume you need them. Our guide on when to use fog lights in Ireland explains the rule.
What the “Auto” setting on your headlights really does
Many newer cars have a light switch with an “Auto” position. In that mode the car turns the headlights on when it’s dark, using a light sensor. That’s a headlight function. It doesn’t switch on your fog lights.
On some cars the fog light switch only works once the headlights are on. If you leave the switch in “Auto” and it’s still daylight, the fog light button may appear to do nothing. In that case, switch the headlights on manually and try again.
Fog lights that switch on for other reasons
Some cars use the fog lights for extra features. For example, some Volvo models can use the front fog lights as cornering lights, lighting up the area diagonally ahead in weak light at low speed, and can switch them on automatically when reversing. Which cars do this, and how, varies by make and model, so check your manual.
If your fog lights seem to come on when you didn’t ask, this is often the reason.
Can you fit fog lights that switch on automatically?
Some people fit aftermarket kits so that the fog lights come on whenever the headlights do. It’s worth thinking twice. In Ireland, the RSA advises that fog lights are used only in dense fog or falling snow, and a fog light left on in clear weather can dazzle other drivers. If you’re considering any lighting change, check with the manufacturer, an authorised dealer or a garage first.
How to check what your car does
- Read your owner’s manual. Look up “fog lights”, “cornering lights” and “automatic lights”.
- Look at the dashboard symbols. A symbol lights up when the front or rear fog lights are on.
- Try the switch. With the car parked, turn the headlights on manually, then press the fog light button and see what lights up.
- Check after driving. Some fog lights stay on until you switch them off, so make a habit of looking at the symbol.
Fog light not working in Auto mode?
If the fog lights won’t come on, try these in order:
- Switch the headlights from “Auto” to the dipped position
- Check the fog light symbol on the dashboard
- Check the bulb, fuse and relay
- Look for a loose connector or moisture in the unit
For the full checklist, see our guide on rear fog light not working. The same steps apply to front fog lights.
Fog lights and the tail lights: what’s the difference?
A rear fog light is much brighter than a tail light, and it’s only for very poor visibility. If you’re not sure how the rear lights differ, read what a tail light is.
Auto fog lights FAQs
Do fog lights come on automatically?
On most cars, no. You switch them on with a button. Some cars have related features, such as cornering lights or an auto headlight mode, so check your owner’s manual.
Why do my fog lights come on when I reverse?
Some cars use the fog lights to add light when reversing, or as cornering lights. It’s a built-in feature on those models. Your manual will say if yours does.
Why won’t my fog lights work in Auto mode?
On some cars the fog light switch only works once the headlights are on. Try switching the headlights on manually.
Should I leave my fog lights on all the time?
No. In Ireland the RSA advises using fog lights only in dense fog or falling snow, and switching them off as soon as visibility improves.
Where can I buy a used fog light?
You can browse used fog lights in Ireland on Autolight, and filter by make, model, year, side and county.
Looking for a fog light?
Browse used car fog lights in Ireland, front and rear, and find the exact fit for your car.
