Fog lights and daytime running lights are those parts of the car you never think about until they stop working. Then suddenly you realise how useful they really were. Fog lights for driving in fog and rain, daytime lights for visibility during the day. Both systems play a role in safety, and when they need replacing, used parts are a smart choice that can save you a tidy sum.
Here is everything you need to know: the types of fog lights and DRLs, how to spot a quality used part, what you can expect to pay, and how to fit them.
Fog lights: what they are and why they matter
Front fog lights sit low in the front bumper. Their key feature is a wide, low beam of light sharply cut off at the top. Why? Because in fog, rain or snow, a high beam from the main headlights reflects off water particles back at you and actually makes visibility worse. Fog lights illuminate the road immediately in front of the car without "hitting" the fog particles above road level.
Beyond their primary role in poor conditions, fog lights are also useful for:
- Lighting up the edges of the road - the wide beam covers ground the main headlights miss
- Driving on winding roads - they fill in the lighting through bends
- Everyday driving - many drivers use fog lights as extra lighting in town (though this is not always legal)
Rear fog lights are mandatory on every car in the EU. Usually it is one strong red light on the left side (or both), used only when driving in fog so drivers behind you can see your vehicle in time.
Daytime running lights (DRL): a legal requirement
Daytime running lights, or DRLs, are lights that switch on automatically when you start the engine. Their sole purpose is to make your car more visible to other road users during the day. Since 2011, every new car sold in the EU must have factory-fitted DRLs.
On older cars, dipped headlights or special bulbs in the main lights take on the DRL role. Many manufacturers use fog lights at reduced intensity as DRLs, which means on some models the fog lights and DRLs share the same housing.
Types of daytime running lights:
- Integrated in the headlight - LED strips or rings inside the main headlight (BMW "angel eyes", Audi LED strips)
- Separate LED modules - standalone LED units mounted in the bumper or below the headlights
- Fog lights with DRL function - fog lights that run at reduced intensity as DRLs
- Modified position bulbs - higher-output position bulbs acting as DRLs (older cars)
Why fog lights and DRLs fail
Fog lights and DRLs have a tougher life than main headlights because they sit low on the bumper, close to the road. That means they are exposed to:
Mechanical damage
Stones from the road are enemy number one. One stone at the wrong time in the wrong place and the fog light glass cracks. On top of that, low-mounted fog lights are the first to take a hit when parking on kerbs, going over high speed bumps or driving on gravel. Even a gentle contact with a kerb can crack the housing or knock the fog light out of position.
Moisture and corrosion
Sitting low, fog lights are constantly exposed to water, mud, salt and road chemicals. Seals age over time and moisture works its way into the housing. Once moisture is inside, it corrodes the reflectors and contacts, and the fog light loses a fair chunk of its effectiveness.
Thermal shock
Picture this: you are driving in the rain, the fog lights are on and hot, then you plough through a big puddle of cold water. The temperature shock can crack the glass or lens. This happens more often than you would think.
Bulb failure and LED degradation
Halogen bulbs in fog lights have a limited service life. Use the fog lights every day and a bulb can burn out within a year. LED daytime lights theoretically last much longer, but in practice LED chips can degrade or stop working entirely due to vibration, thermal cycles or a bad solder joint on the board.
How much do used fog lights and DRLs cost?
Fog lights are generally affordable parts, even new. But when you need a specific fog light for a newer model with integrated LED DRL, the price of a new part can catch you off guard.
Classic halogen fog lights (used)
- Most models up to 2015 - EUR 10 to 30 each
- Premium brands (BMW, Audi, Mercedes) - EUR 20 to 50 each
Fog lights with integrated LED DRL (used)
- VW Golf 7, Passat B8 - EUR 30 to 70 each
- BMW 3/5 Series (F30/F10) - EUR 40 to 100 each
- Audi A3/A4 (2013+) - EUR 40 to 90 each
Separate LED DRL modules (used)
- Standard models - EUR 20 to 50 each
- Premium models - EUR 30 to 80 each
For comparison, a new fog light with LED DRL for a BMW F30 costs around EUR 150 to 200. A used one in good shape goes for EUR 50 to 70. That is a saving of over EUR 100 per unit, and you need two of them.
What to look for when buying used fog lights
Fog lights are relatively simple parts, but there are still a few things to pay attention to:
Glass or lens
Must be clean, with no cracks and no fogging on the inside. Even a small crack means moisture will get in and chew up the insides. Check carefully under strong light.
Reflector
The inner reflector must be shiny and clean. A darkened or peeling reflector means the fog light will not aim its beam properly and is essentially useless for its primary function.
Mounts and clips
Fog lights are usually mounted in the bumper using plastic clips or metal brackets. Check that every bracket is intact and that no clips are broken. A broken bracket means the fog light will not sit firmly and will vibrate, which affects beam quality and accelerates wear.
LED functionality
If you are buying a fog light with integrated LED DRL, make sure every LED segment works. Individual LEDs cannot be replaced, so if one is dead, the part is useless for that function. Ideally, test it on a 12V battery before buying.
Bumper compatibility
Fog lights are designed for specific bumpers. If your car had a facelift (a mid-cycle refresh), pre- and post-facelift fog lights are usually not the same. Confirm the exact year and trim variant.
Fitting used fog lights
Replacing fog lights is a job you can do yourself, but it takes a bit more patience than swapping a main headlight because the fog lights live in the bumper.
On most cars, the fog lights are accessible from below or through an opening behind the front wheel arch. The procedure usually looks like this:
- Lift the car on a jack or ramps so you have access from underneath
- Remove the under-bumper splash shield (if fitted)
- Unplug the electrical connector from the fog light
- Undo the screws or turn the bayonet ring holding the fog light
- Take out the old fog light and slot in the new one
- Connect the plug and secure the fog light
- Refit the splash shield
On some models (especially newer ones with integrated DRL), getting to the fog light means removing part of the bumper or the wheel arch liner. It is not hard, but it takes longer.
After fitting, check the beam aim. Fog lights must point straight ahead or slightly down. Never up, because you will dazzle oncoming drivers, which is both dangerous and illegal.
Where to get used fog lights and DRLs
The fastest and most reliable way is to send an enquiry to PoDi. Specify the car model, year and exactly which part you need (front fog light, rear fog light, DRL module), and you will get quotes from suppliers who have that part in stock.
Alternatively, fog lights turn up often at scrapyards because bumpers are frequently replaced after crashes, and the fog lights in them are usually intact. Drop in to your local scrapyard and ask if they have a bumper with fog lights for your model, because sometimes it is cheaper to buy a whole bumper with the fog lights than to buy a single fog light on its own.
Small parts, big safety contribution
Fog lights and daytime running lights are small but important parts that contribute to your safety on the road. Used examples are an excellent option because they are mechanically simple, easy to check and significantly cheaper than new. Whether you need a classic halogen fog light or a more modern LED DRL module, send a request to PoDi and find the right part for your car quickly and at a fair price.