Malfunctioning turn signals – also referred to as blinkers – can often be more than a slight inconvenience, considering their impact on driver safety and the risk of potential traffic violations. Without these blinkers, you can’t tell other drivers which direction you’re turning in. This can not only compromise your safety but also lead to traffic violations that result in hefty fines. 

In this guide, we’ll cover the essential details on how to fix the problems, starting with specifications about your vehicle class, associated components, and potential symptoms you may come across. 

The Mercedes-Benz A-Class series consists of the W177 (hatchback) and V177 (sedan), both of which are renowned for their luxury compact design, MBUX infotainment system, and advanced lighting systems that feature LED high-performance headlights, sequential dynamic turn signals in the side mirrors, and standard lights at the front and rear. 

When these turn signals fail, they can affect interconnected components, such as LED headlights. 

Impact of Turn Signal Warning Error on LED Headlights 

When your turn signals fail to work adequately, it can trigger a chain reaction that often affects nearby components, such as LED headlights. Both of them work together through a vehicle’s electrical system, which directs power to each function.

Without each of these essential components, you compromise nighttime visibility and are unable to alert other roadside drivers in which direction you’re turning, let alone which lane you’re changing to.

In the case that you have digital LED headlights, the turn signal warning can also affect headlight operation, potentially reducing maximum light output. These advanced headlights are controlled by a digital micromirror device chip, which may begin to dim or flicker when the turn signal warning is flashing. The potential side effect makes it crucial to understand the turn signal malfunction you’re dealing with further. 

What Does The Left-Right Turn Signal Warning Error Mean

When the “Left/Right Turn Signal Malfunction” warning appears on the dashboard of your Mercedes-Benz W177 or V177, it can indicate the existence of a faulty unit that may cause the headlight to malfunction. 

You’ll also find that the defective front turn signal won’t work at all or blink sporadically. This may also cause the dipped beam headlights to fail to function, making it highly unsafe and compromising safety while driving at night. When you notice signs, make sure to address the issue promptly. 

Reason Behind Front Left/Right Turn Signal Warning 

The turn signal malfunction is due to a failed LED module because: 

Lifespan degradation: This is a gradual deterioration process in which the sensitive components of the LED module fail due to continuous heat, vibrations, and electrical stress. This can cause the LED module to fail eventually, causing the front turn signal to stop working entirely. Beyond turn signals, this can also impact LED headlights and the dipped beam function. 

Other potential reasons include: 

  • External damages, such as a car accident or a natural phenomenon. 
  • Moisture ingress due to a cracked headlight seal. 

Potential Symptoms Of Front Turn Signal Malfunction

Beyond a warning error illuminating on your dashboard, you can also experience the following symptoms: 

  • Depending on the fault side, the defective turn signal won’t work. 
  • You may also experience related warning messages, like “Front Right Turn Signal” and “Right Low Beam.”
  • Other interconnected lights under the same module may also fail to function properly. This includes adjacent LED headlights, dipped beams, and more. 

How To Fix The Issue

A direct replacement of the faulty LED module can help remove the “Front Left/Right Turn Signal” warning. Before making a purchase, make sure the faulty LED module part number aligns with the one you’re planning to replace it with. This can help ensure compatibility and a seamless installation process. 

At Xenons4U, we offer the Mercedes-Benz A2139007839 LED Module, which is factory-fitted to many different Mercedes-Benz cars with LED high-performance headlights. If you’re looking for a different part number, our team can also assist with that. 

After replacement, diagnostic coding is required with DealerStar in order to remove the error code on your dashboard. Without it, the warning error will persist– regardless of whether you’ve replaced the faulty module or not. 

If you run into any problems during the installation process, contact our team of specialists for professional insights. 

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