What Causes BMW Low Beam Malfunction? (Here’s What To Do)

Low beams are an essential part of safe driving. If those lights malfunction, you will be forced to turn on the high beams of your BMW on dark roads. This can visually shock the oncoming traffic and cause accidents. So, all drivers should take fast action if their low beams cease to work properly. 

So, what causes bmw low beam malfunction? In most cases, the fault is usually within the bulb. Maybe they have run their course and need changing. Another common reason is a bad control unit. Fuse, switch, relay, and wiring problems can also be contributing factors. 

You will put everyone at risk when you drive with low-beam failure at night and on foggy roads. However, proper knowledge can help you resolve the issue at lower costs and effort. 

5 Possible Reasons Behind Bmw Low Beam Malfunction With Solutions

Your issue starts with the BMW displaying a low-beam malfunction message on its dashboard. Bulbs and control units are usually the commonest sources of the problem. 

So, these should be the first components you check. If they are okay, consider other relevant parts of your vehicle. 

1. Bulbs Past Their Prime

When your bulbs reach the end of their service span, they will blow out. However, road impact and environmental factors can shorten their life. This is why you might see one factory-fitted bulb going bad before the other. 

Replacement is the only option when you have a blown-out bulb. It is a fairly easy job. You just have to access the bulb compartment, pull out the socket, remove the old bulb, and put in the new one. 

Depending on the model, you can access the bulb by turning the front wheels or opening the bonnet. 

The retail rates of xenon or halogen low-beam bulbs are usually around 20-30 dollars. However, BMW-manufactured model-specific bulbs can cost you ten times more than this price. 

If you are on a budget or facing an emergency, cheaper alternatives are acceptable. Otherwise, it’s best not to use products from other manufacturers with your BMW.

Read Also: What Causes DBC to Malfunction on BMW? [Diagnosis & Fix]

2. Ballast Failure

The Xenon light control unit or ballast ignites the lamp and then maintains the voltage. As a result, these units regulate the intensity of the bulbs. The component also determines how much battery power the low-beam uses. 

Usually, the ballast is a square or rectangular-shaped box. You will find it attached to one side of the headlight compartment. 

They replace a lot of complex circuitry needed to regulate the bulbs. Thus, they make the light control in your BMW smarter and more automated. 

Power spikes, driving impacts, and other factors can damage the unit. To determine whether a damaged unit is the cause of your malfunction, perform a simple test. 

Swap bulbs between the functioning and nonfunctioning side. If the bulb from the working side fails to light up on the other side, the problem’s probably within the ballast. 

Recent history of a flickering and blinking lamp on the affected side confirms the doubt. 

The price of xenon control units varies across models. Older models with less complex units might cost as low as 20 dollars. 

However, the recent vehicle requires complex units that can go as high as 300 dollars. For the full estimation, also add the labor costs (150-200$). 

Read Also: Reasons For BMW Left Brake Lamp Malfunction | Fix Now!

3. A Problem in the Fuse Box

The fuse is an old, simple, cheap, yet extremely effective measure to protect your car’s internals. 

It breaks off the electrical connection between your battery and the low-beam bulbs when there’s a power surge. As a result, the bulbs and relevant circuits are spared from becoming fried. 

Consider checking your fuse box if your bulb and Xenon control unit isn’t the source of the malfunction. 

Depending on the model, your BMW fuse box might either be in the bonnet or past the dash. After locating the box, open it to inspect the condition and make replacements accordingly. 

You will need the help of your BMW manual to chart the arrangement of fuses in the box correctly. Although, it’s not that hard to identify a burnt fuse. They will look smeared or destroyed compared to the intact ones. 

BMW fuses are some of the cheapest parts to replace in the car. They usually cost 10-20$. However, you may have to count some labor costs (50-100$) if you cannot figure out the arrangement. 

Read Also: Why BMW Lane Departure Warning Malfunction? Causes & Fixes

4. Headlight Switch and Relay faults

The headlight switch is on the left of the steering wheel. Turning it on sends a signal to the body control module. The module responds to the signal and turns the headlight switch relay on. This completes the circuit and lights your lamps. 

A fault with the switch or the relay will prevent your low beams from coming on. Simple observation lets you easily detect whether it’s the switch or relay to blame. 

In case of a failing switch (with an intact relay), the malfunction will be unpredictable. This means the bulbs will light on some occasions and not on others. 

Whereas if the relay fails, the bulbs will not work. Plus, the clicking sound you hear after flipping the switch will be absent. 

The cost of the relay is around 30-40$. You will find it in the fuse box. However, the costs will be much higher if the switch goes bad. Considering parts and labor costs, you may have to spend around 300$.

5. Connection Problems

Corroded and decaying wires can always be the source of a low beam malfunction. Light control units and related modules have significantly reduced the number of wires in your BMW. 

But still, there are an awful lot of wire connections that are vulnerable to rust and corrosion. 

After making sure the low beam malfunction is not due to any of the factors above, you can consider damaged wires. Inspect the headlight housing for soft greenish-white powder, which indicates corrosion. 

Here, your best option is to take the car to a mechanic. They can take the car apart if needed and correct the wiring problems. 

Read Also: BMW Passenger Restraint System Malfunction: Reasons & Fixes

What Are The Risks of Driving Your BMW with A Broken Low Beam? 

The major risk of driving with a broken low-beam lamp is blinding the oncoming traffic and causing an accident. If your low beams malfunction at night, there’s no option but to flash the high beams. 

This can temporarily blind the drivers coming from the opposite side and result in a collision.

In addition, the law also considers driving without a functioning low beam a risky behavior. Therefore, the patrolling officers can pull the vehicle over and take legal action against the driver. 

Lastly, you will endanger yourself even on roads with light traffic. Various roadside structures are designed to reflect off the light of low beams. Flashing a high beam on them will cause too much reflection and visually impaired you. 

Some Tips To Make Your BMW Low Beams Last Longer 

Your BMW low beams will last longer when you properly care for the vehicle. So, if you want your lamps not to go bad before their expected lifespan, follow these tips- 

  • Inspect your fuse box once a year and consider a replacement if the fuse looks worn out. 
  • Every six months, take your car to the repair shop to inspect the wiring, headlight housing, and bonnet. Although this might cost you around 100$, this lets you take early measures to avoid expensive repairs.
  • Keep your car clean and prevent the build-up of moisture and debris.
  • Use BMW-manufactured parts for any kind of replacement.
  • Practice safe driving. Rough driving impacts the internals of your BMW and also causes power spikes. 

Read Also: Cause & Fix For BMW Emergency Call Malfunction


The above discussion answers many queries related to a low beam malfunction on your BMW. You still might have some questions which we are eager to answer. 

How much does it cost to fix your BMW low beams? 

If the cause of the low beam malfunction is a cheap part like the fuse or relay, you can be done within 30$. But you must be familiar with your vehicle’s fuse box. Bulb, Control unit, or headlight switch replacement can cost 250-300$. 

Do I have to change both low-beam bulbs? 

When the issue is explicitly the bulbs, it’s best to change both. Considering the factory fitted both bulbs on the same date, one failing bulb will mean the other has also run its course. So, replacing both sides will save you time and labor costs. 

How long do BMW low beams usually last?

The type of bulbs used in your BMW varies according to model. But most of these vehicles have Xenon or Halogen bulbs. Xenon bulbs, which emit a bluish light, last approximately 2400 hours. Meanwhile, Halogen bulbs have a lifespan of 500-1000 hours. 

Why do my BMW low-beam bulbs not light up equally?

The low-beam bulbs are supposed to be asymmetrical. The left side will illuminate less than the right. This is because the oncoming traffic is on the left side. But if the inequality is too apparent, it might be because you used a non-BMW bulb.

Final Thoughts 

A bmw low beam malfunction is not something you can put away to deal with later. Some drivers might think, ‘hey, I still got the high beams working for me.” 

But they will soon discover the fault in their thinking when cops pull them over. Or, even worse, they might get into an accident. As a BMW owner, you must familiarize yourself with your vehicle’s fuse box and headlight housing. 

This can help you to minimize the labor costs during various replacements. Don’t forget to wear gloves and use proper tools when conducting operations on your car.

Similar Posts