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ABS/ESP Warning Lights On 2021 GLC 300 - What's Going On?

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Christine P. · rep 0 · May 22, 4:15 AM · 1 replies · solved · Question

Vehicle: 2021 Mercedes-Benz GLC 300

Hey everyone,

My 2021 Mercedes-Benz GLC 300 recently lit up with both the ABS and ESP warning lights on the dash. Sometimes the traction control light comes on too. It happened suddenly, and now they're just staying on. I haven't noticed any immediate changes in braking performance, but it's definitely concerning.

I'm wondering if this is a common issue with the GLC or if it points to something specific. Could it be a sensor, or something more serious with the braking system? I'd appreciate any advice before I head to the dealership.

Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:15 AM

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ClearTheCode admin answer:

When the ABS (Anti-lock Braking System) and ESP (Electronic Stability Program) warning lights illuminate simultaneously on your 2021 Mercedes-Benz GLC 300, it indicates that these critical safety systems have been deactivated or are experiencing a fault. This means your vehicle's ability to prevent wheel lock-up during hard braking and maintain stability during skids is compromised.

  1. Common Causes:

    • Wheel Speed Sensors: This is the most common culprit. Each wheel has a speed sensor that monitors its rotation. If one sensor fails, becomes dirty, or its wiring is damaged, the ABS/ESP system loses crucial data, triggering the warning lights. Common OBD codes include C0031 (Left Front Wheel Speed Sensor), C0034 (Right Front Wheel Speed Sensor), C0037 (Left Rear Wheel Speed Sensor), or C0040 (Right Rear Wheel Speed Sensor).
    • ABS Control Module Failure: Less common, but the ABS control module itself can fail, leading to system errors.
    • Brake Light Switch: A faulty brake light switch can sometimes confuse the ESP system, as it's part of the input for braking.
    • Steering Angle Sensor: The ESP system uses the steering angle sensor to determine the driver's intended direction. A fault here can trigger the ESP light.
    • Low Brake Fluid: While less likely to trigger ABS/ESP directly without a separate brake warning, extremely low fluid can sometimes cause issues.
    • Blown Fuse: A fuse related to the ABS/ESP system could have blown.

  2. When to See a Shop:

    • Immediately: Since these systems are vital for safety, it's highly recommended to have your vehicle inspected by a Mercedes-Benz specialist as soon as possible. While your regular braking might feel normal, the ABS and ESP functions are disabled, which can be dangerous in emergency situations or adverse weather conditions.
    • Diagnostics: A professional will connect to your vehicle's OBD-II port to retrieve specific fault codes. These codes are essential for accurately diagnosing the problem, as they will point directly to the faulty sensor, module, or circuit. Do not ignore these warning lights, as they indicate a significant safety concern.
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