It can be confusing when the “Light/Right Low Beam Malfunction” warning flashes on your dashboard and you’re stuck debating your next steps. This warning is often reported by many Mercedes-Benz drivers, especially those who own the A-Class series. It features two high-performance models, the W177 (a five-door hatchback) and the V177 (a four-door sedan).

Both of which are renowned for their modern exterior and advanced LED headlight system, with options ranging from high-performance LEDs to sophisticated adaptive systems. The latter may raise issues, like the occasional warning message that flashes across your dashboard. 

Read on to learn what your next steps should be when the “Left/Right Low Beam Malfunction” flashes across your dashboard. 

The Affected Component: LED Headlamps

The headlight system in the Mercedes-Benz A Class W177 V177 models features high-performance LED headlights, individual LED control, and adaptive high and low-beam assist, providing bright, efficient illumination that automatically adjusts to surrounding traffic and dim-light road conditions. 

Owners can also choose from optional Digital LED lights that provide computer-controlled, high-definition lighting. Irrespective of the type of headlight your W177 or V177 has, there’s always a chance of the “Left/Right Low Beam Malfunction” appearing on your dashboard - making it crucial to learn what the error means. 

What Does “Left/Right Low Beam Malfunction” Mean?

When the Electric Control Unit (ECU) in your car detects a fault with either module (left or right) that controls your low-intensity dipped beam lights, it will trigger a warning message on the dashboard. In this case, it can be either of the two: 

  • Front Right Turn Signal
  • Right Low Beam

When the malfunctioning error pops up, the low-beam function on either side of the vehicle will stop working. These lights are integral to your safety and should always be in working order during nighttime driving, especially when crossing through a tunnel or indoor parking lot. 

Reasons For Warning Error

The culprit behind the warning error on your dashboard is likely due to an LED module failure, which is typically caused by:

Lifespan degradation: Due to either heat or electrical overstress (EOS), LED modules in vehicles can gradually fade over time. A phenomenon, commonly known as lumen depreciation, where the original light source diminishes over a period of time. This can be highly concerning as it can eventually cause your low-beam headlights to stop working entirely, putting your safety and that of others at risk during nighttime driving. 

Other potential causes include external damage to the headlight LED module, moisture ingress from car washes, or loose connectors that disrupt the flow of power from reaching the LED headlights. 

Potential Symptoms of Warning Error “Left/Right Low Beam Malfunction.”

When experiencing a malfunction with your low beam headlights, you may come across the following symptoms:

Warning message: You’ll receive a warning error on your dashboard, indicating that either the left or right low headlights are malfunctioning. It can be either “Left/Right Low Beam Malfunction.”

Low beam lights won’t work: During this phase, the affected low beam lights will fail to work completely or blink sporadically until the issue is resolved. 

Connected lights won’t work: Beyond low beam headlights, the LED module is responsible for a range of lighting components, like parking lights or DRLs. 

How To Fix The Issue 

A replacement of the faulty LED module will help get your low beam headlights back into working condition. If you’re unsure whether the LED module is at fault, you can take advantage of an OBD2 scanner to recognise the fault and read the codes it provides to determine the root of the problem. 

Once you have assessed the error, you can purchase a new LED module that perfectly aligns with the part numbers of your old, faulty one. At Xenons4U, we offer the Mercedes-Benz A2139007839 LED Module that is a factory-fitted replacement. Suitable for a range of Mercedes-Benz models with high-performance LEDs, notably the W177 and V177. 

After replacement, diagnostic coding with the DealerStar software is mandatory. Without it, the module will fail to work, and the warning error will persist on your dashboard. If you run into any complications during the installation process, contact our car specialists for professional advice. 

Compatibility List & Part Number

Our module offers a broad compatibility range: 

  • Software Hardware part numbers:
    • HW-NR A2139019615
    • SW-NR A2139022927
  • Mercedes-Benz part number:
    • A2139007839
  • Continental part number:
    • A2C7822670500
  • More compatible part numbers
    • A2139008139
    • A2C7822720500
    • HW-NR A2139019915
    • SW-NR A2139022927
  • Compatible Mercedes-Benz A class W177 V177 LED High Performance Headlamps
    • A1779064606
  • Compatible Mercedes-Benz cars
    • A class W177 Facelift Hatchback
    • A class V177 Facelift Saloon Sedan
    • 2023 2024 2025
    • A250e Hybrid
    • A180d A200d A220d diesel 
    • AMG Line
    • A160 A180 A200 A220 A250 4MATIC Petrol Gasoline
    • A35 A45 AMG
    • GLE V167 Facelift
    • 2023 2024 2025
    • GLE350 GLE450 GLE450e GLE580
    • GLE53 GLE63 AMG
    • GLB X247 Facelift
    • 2023 2024 2025
    • GLB250
    • GLB35 AMG