Guide to the 2017-2025 Audi A4 Quattro ABS Wheel Speed Sensor
Understand why your ABS and ESC lights are on and how to choose the right replacement sensor for your A4.
- A combination of ABS, ESC, and brake warning lights is the most common sign of a failed sensor.
- Driving is possible, but key safety systems are offline; repair should not be delayed.
- A TSB exists for this issue, suggesting cleaning the sensor and ring before replacement.
- High-quality aftermarket brands like Delphi and Beck Arnley are reliable, cost-effective alternatives to OEM.
- An OBD-II scanner is highly recommended to confirm which specific wheel sensor has failed before ordering a part.
Is a Warning Light on Your Dash?
A sudden cluster of warning lights on your Audi A4's dashboard—specifically the ABS, ESC (traction control), and sometimes the brake warning light—often points to a single, common problem: a failed ABS wheel speed sensor. While it looks alarming, this is a frequent issue on many vehicles, and it's usually straightforward to fix. This guide will walk you through the symptoms, how to choose the right aftermarket part, and what to expect for the repair.
Don't Ignore the Lights
While you can still drive the car, your primary safety systems like ABS and stability control are disabled. This means your wheels can lock up during a hard stop, increasing the risk of skidding and losing steering control. It's recommended to get the issue diagnosed and repaired promptly.
Symptoms of a Failing ABS Sensor on an A4 Quattro
A bad wheel speed sensor sends incorrect or no data to your car's main computer. This can cause a chain reaction of system warnings. Look out for:
- ABS Light On: This is the most direct symptom. The system has detected a fault and disabled itself.
- ESC/Traction Control Light On: Because the stability and traction systems rely on the same wheel speed data, they will also shut down and trigger a warning light.
- Parking Brake Malfunction Warning: On some B9 A4 models, a faulty ABS sensor can also trigger an electronic parking brake error.
- Braking and Stability Issues: You might notice the brakes feel different or the car is less stable in wet or snowy conditions because the safety systems are not active.
Choosing the Right Aftermarket ABS Sensor
For the 2017-2025 Audi A4, you don't always need to pay dealership prices for an OEM part. High-quality aftermarket brands offer reliable alternatives that meet or exceed original specifications. Here’s a look at the available options:
Tier 1: OEM-Level Quality
- Delphi: Delphi is a well-respected manufacturer that often supplies original parts to automakers. Their sensors are known for using the latest digital signal technology for accuracy and have weather-pack connectors to resist corrosion, a common failure point. For an Audi, a Delphi sensor is a top-tier choice that provides confidence and longevity.
Tier 2: Reliable Aftermarket
- Beck Arnley: This brand specializes in sourcing parts that match the original's form, fit, and function, often from the same factories that make the OEM parts. They are a trusted name for import vehicles and provide a quality part that is a direct plug-in replacement.
- Standard Ignition (SMP): Standard is a large, established American aftermarket company. Their parts are a dependable, cost-effective alternative to OEM and are widely available.
Pro Tip: Check the Part Number
Front, rear, left, and right sensors can have different part numbers. Always verify the exact part number for the specific wheel you are replacing. An OBD-II scanner can tell you which sensor has failed, for example, "Front Right Wheel Speed Sensor Implausible Signal."
Cost of Replacing an Audi A4 ABS Sensor
The cost is reasonable, especially if you do the work yourself. The part itself is not expensive, and labor is minimal for a professional mechanic.
| Part / Service | Estimated Cost |
|---|---|
| New OEM Sensor | $88 - $196 |
| New Aftermarket Sensor | $48 - $84 |
| Shop Labor | $53 - $95 |
| Total (DIY) | $48 - $84 |
| Total (Shop) | $141 - $274 |
Frequently Asked Questions
Can I replace just one ABS sensor?
Yes. You only need to replace the sensor that has failed. A diagnostic scan will identify the specific sensor causing the issue. Unlike brake pads or tires, there is no need to replace them in pairs.
Is replacing an ABS sensor a difficult DIY job?
For most DIYers with basic tools, this is a manageable job. The process involves jacking up the car, removing the wheel, undoing a single bolt holding the sensor, and disconnecting the electrical plug. The main challenge can be if the old sensor is seized in the wheel hub due to rust or debris.
What is a TSB for the ABS sensor?
Audi has issued Technical Service Bulletin (TSB) 2072304/1 for an "implausible signal" from the ABS/ESC speed sensor. It states that dirt, grease, or debris on the sensor or the sensor ring on the wheel bearing can cause a fault. Before replacing the sensor, it's worth inspecting and cleaning the area to see if that resolves the issue.
Do I need to reset the computer after replacing the sensor?
Often, the warning lights will turn off on their own after a short drive once the new sensor is installed. However, the fault code will remain stored in the ABS module's memory. It is best practice to use an OBD-II scanner to clear the codes after the repair is complete.
Technical Specifications
OEM Part Numbers: WHT003860 WHT003860B 4M0927807N
The sensor is a magnetic or Hall effect sensor that reads a toothed reluctor ring on the wheel hub assembly. It is secured by a single bolt and connects to the main wiring harness via a weather-proof electrical connector.
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 A4 Quattro: