A Guide to the ABS Wheel Speed Sensor for the 2008-2018 Audi A5 Quattro
Understanding the common failure signs and choosing the right replacement ABS sensor for your A5 Quattro.
- A bad ABS sensor will disable your ABS and ESP/Traction Control systems, indicated by warning lights on the dash.
- Use a scan tool to identify which specific sensor has failed before buying parts.
- Pay close attention to your vehicle's model year to choose the correct part for the B8 (2008-2017) or B9 (2018) generation.
- Choosing a quality brand like Bosch or Hella is recommended to ensure reliability and avoid repeat repairs.
Understanding ABS Sensor Failure in Your A5 Quattro
A failing ABS wheel speed sensor is a common issue on many vehicles, including the Audi A5. These sensors live in a harsh environment near the wheel hub, exposed to water, dirt, heat, and road debris. Over time, this exposure can lead to corrosion, damage to the sensor or its wiring, or an internal electronic failure. Sometimes, the problem isn't the sensor itself but metallic debris or dirt on the magnetic ring (tone ring) that the sensor reads. When a sensor fails, it can no longer send accurate speed data to the car's safety systems.
Symptoms of a Bad ABS Wheel Speed Sensor
The signs of a bad wheel speed sensor are usually very clear. You will almost certainly see warning lights on your dashboard. The most common symptoms include:
- ABS Warning Light: The 'ABS' light will illuminate and stay on. This indicates the anti-lock braking system is disabled.
- Traction/Stability Control Light: The 'ESP' (Electronic Stability Program) or traction control light (a car with squiggly lines) will also light up.
- Brake System Warning: In some cases, a general brake warning light may also appear.
- Loss of ABS Function: During emergency braking, your wheels may lock up and skid, as the anti-lock function will be inactive.
- Loss of Traction Control: Your wheels may spin more easily when accelerating on wet or loose surfaces.
Known Issue: Wiring Corrosion (TSB 2033412/3)
Audi issued a Technical Service Bulletin (TSB) for some vehicles regarding the ABS wheel speed sensor wiring. The wire insulation near the left front wheel well could be damaged from the factory, allowing moisture to cause corrosion. This can lead to an 'Incorrect Signal' fault code (like DTC 0283) and trigger the ABS/ESP lights. Before replacing a sensor, it's wise to inspect the wiring harness for any visible damage or corrosion, especially on the front left side.
🎬 Watch: Common causes for Audi ABS and traction control lights.Choosing the Right Aftermarket ABS Sensor
When replacing the sensor, you have several brand choices. Quality can vary, so it's important to choose a reputable brand to avoid having to do the job twice. For a critical safety part like this, saving a few dollars on a low-quality sensor is often not worth the risk.
Brand Quality Tiers
- OEM-Quality Brands (Top Tier): These brands are often the original suppliers to Audi or have a reputation for matching OEM quality and reliability. They are the most recommended choice for a trouble-free repair.
Brands: Bosch, Hella - Reliable Aftermarket Brands (Mid Tier): These brands offer a good balance of quality and price. They are well-known in the industry and are generally a safe bet for most owners.
Brands: Delphi, Vemo, Standard Ignition, Beck Arnley - Budget Brands (Economy Tier): These brands are the most affordable, but quality and fit can be inconsistent. They may be an option for those on a tight budget, but be aware of mixed reviews for electronic parts.
Brands: URO Parts, Facet, Bremi
Ordering the Correct Part: B8 vs. B9 Generation
The 2008-2018 model years span two different A5 generations: the B8 (2008-2017) and the B9 (2018). These generations use different ABS sensors. For example, B8 part numbers often look like 4E0927803D, while B9 part numbers look like 4M0927803C. Always verify the part 🎬 See this step-by-step sensor replacement on a B8 Audi. fits your specific year and submodel before ordering.
Cost of Replacing an Audi A5 ABS Sensor
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $28.86 - $94.32 |
| New OEM Sensor | $90 - $210 |
| Shop Labor | $50 - $95 |
| Total (Shop Repair) | $140 - $305 |
Frequently Asked Questions
Can I drive my A5 with the ABS light on?
Yes, but with caution. Your primary braking system will still work, but the anti-lock (ABS) and stability control (ESP) safety features will be disabled. This means your wheels can lock up in a panic stop, and you won't have the car's help to prevent skids. It is highly recommended to get the sensor replaced as soon as possible.
Do I need to replace all four sensors at once?
No. You only need to replace the sensor that has failed. A diagnostic scan tool can read the fault codes from the ABS module to tell you exactly which wheel sensor is causing the problem (e.g., 'Left Front Wheel Speed Sensor').
Is this a difficult DIY repair?
For a DIYer with some experience, this is a relatively easy job. It typically involves removing the wheel, locating the sensor, removing a single bolt (usually a 5mm hex), and disconnecting the wire. However, sensors can sometimes seize in the wheel hub due to rust and may require extra effort to remove.
What tools do I need to replace the sensor?
You will need a jack and jack stands, a lug wrench to remove the wheel, a set of metric sockets, and a 5mm hex (Allen) bit socket. It's also helpful to have some penetrating fluid on hand in case the old sensor is stuck, and a wire brush to clean the mounting hole.
🎬 Watch: A quick guide on how to replace the sensor.Helpful Videos
Technical Specifications
OEM Part Numbers: 4E0927804D 4E0927803D 4M0927803C 4M0927807C
The ABS wheel speed sensor for the Audi A5 Quattro is a magnetic or Hall effect sensor that mounts to the wheel hub/steering knuckle. It is held in place by a single 5mm hex bolt and connects to the main wiring harness via a plastic connector. Part numbers differ between the B8 (2008-2017) and B9 (2018) generations.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Audi A5 Quattro:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Understanding ABS Sensor Failure in Your A5 Quattro
- Symptoms of a Bad ABS Wheel Speed Sensor
- Known Issue: Wiring Corrosion (TSB 2033412/3)
- Choosing the Right Aftermarket ABS Sensor
- Brand Quality Tiers
- Ordering the Correct Part: B8 vs. B9 Generation
- Cost of Replacing an Audi A5 ABS Sensor
- Frequently Asked Questions
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