Solving BMW’s ABS Issues: Understanding the Wheel Speed Sensor

If your BMW ABS, brake, DSC, DTC, or ASC lights come on, along with a message on the iDrive screen reminding you to get your BMW serviced, your BMW ABS wheel speed sensor may need to be replaced. Usually, the three lights, ABS, traction, and brake light, come on as soon as you start to drive. Sometimes, the three lights may come on after a few minutes of highway driving.

In this guide, we look at BMW ABS wheel speed sensor problems, how to diagnose them, and how to clean them. A how-to video shows you how to replace the BMW ABS sensor (also called the BMW ABS wheel speed sensor or speed sensor for short).

A BMW wheel speed monitors the wheel’s revolutions and sends a signal to the ABS/DSC module. The BMW ABS sensor determines wheel revolutions per minute (rpm).

Symptoms

The most common symptom of a bad BMW ABS wheel speed sensor is three warning lights on the dashboard:

1. ABS,
2. Brake
3. DSC, ASC, DTC light on.

Other symptoms may also indicate that your BMW ABS sensor is defective. Below is an extensive list of symptoms that you may notice if your BMW wheel speed sensor is bad:

• ABS light on
• Anti-lock braking disabled
• DSC or ASC light on
• Dynamic Brake Control Disabled
• DBC Malfunction Drive Carefully
• Intermittent speedometer failure
• The traction control system was disabled.
• Transmission going into limp mode.
• Transmission Failsafe
• Intermittent activation of ABS when applying brakes
• The engine will not rev above 5,000 rpm.
• The speedometer displays double the actual speed,
• ABS light flicking on and off
• Check engine light on with code P0500
• Message on iDrive asking you to service vehicle

Check engine light, odometer, cruise control, and speedometer not working are possible but less likely.

How to Diagnose BMW ABS Wheel Speed Sensor

The YOUCANIC Full System Scanner can diagnose your BMW’s control modules, including the ABS wheel speed sensor.

An extra step you can perform to verify that your BMW wheel speed sensors work is to use the scanner to display the actual value from all four of the wheel speed sensors. A generic OBD2 scanner will not read/clear BMW DSC or ABS module fault codes. Before you replace the ABS sensor, consider swapping front wheel speed sensors and rechecking failure codes. Clear any stored code and monitor the codes that return.

• The fault code has moved to the opposite wheel, confirming the ABS sensor’s problem.
• The fault code remains with the same wheel/sensor. You may have a wiring issue.

Another method to test BMW wheel speed sensors is to use a digital multimeter and measure resistance. Remove each wheel one at a time. Disconnect the ABS sensor wire and measure the resistance of each sensor.

ABS sensor resistance should measure around 1000 ohms. Compare all the resistance readings from all the sensors. This will help you determine which has failed. Usually, only one of the sensors fails at a time. It is uncommon for more than one sensor to fail.

How to Replace a BMW ABS Wheel Sensor

Below, you will find step-by-step instructions on how to replace the BMW wheel speed sensor.

What you will need

• BMW Wheel Speed Sensor
• Hex wrench set
• Penetrating oil
• Wire brush
• Car Jack
• Jack Stand

Procedure

1. Loosen up the lug nut. Jack up the vehicle and secure it with jack stands. Remove the wheel.
2. Locate your BMW wheel speed sensor on the back of the wheel hub.
3. Trace the ABS sensor wire to the black box where you will find the connector. Open the box by flipping the top cover.
4. Disconnect the ABS weed sensor wire. The connector is held in place with two small locking tabs. Press the two tabs, then pull apart the connector. Note that next to the ABS sensor, you have the connector for the brake pad wear sensor. The connector for the brake pad wear sensor is white.
5. Remove the bolt that secures the ABS sensor to your BMW hub. On most BMWs, this will be a 5mm hex bolt.
6. Remove the ABS sensor wire from the front strut bracket.
7. Install the new BMW wheel speed sensor, ensuring the wire is routed correctly. If you route the wire incorrectly, it will get stretched and damaged when the wheel is turned.
8. Clean any rust from the ABS wheel speed sensor hole using a wire brush. Insert the ABS wheel speed sensor into the wheel hub and screw the bolt.
9. Tighten the ABS wheel speed sensor bolt to 10Nm.

Note: The codes may still be stored in the DSC module but will change from Present to Stored status.

Once you replace the ABS sensor, start the car and turning the steering wheel left and right. Repeat the procedure a couple of times. As you start driving the vehicle, your ABS / DSC / TSC / Brake lights should reset if no other fault codes are present.

Cleaning BMW Wheel Speed Sensor

In a few cases, the sensor’s tip can collect dirt and debris, which prevents the sensor from operating properly. Remove the sensor and clean dirt and any metal particles from the tip of the sensor. Take the wheels off and look at your BMW ABS speed sensor wires. Replace the sensors if any insulation is cracked or bare wire is exposed.

Replaced BMW Wheel ABS Sensor; light is still on

If you have replaced the ABS wheel speed sensor on your BMW, but the ABS light or brake light is still on, there could be several reasons why the problem persists. It may be due to a faulty installation or a damaged wiring harness that needs repair. Another possible cause could be a malfunctioning control module or ABS hydraulic unit, requiring a more complex repair. It’s also possible that the new sensor itself is defective and needs to be replaced again. To accurately diagnose the problem, it is recommended to have the vehicle inspected by a BMW-certified mechanic or a professional diagnostic tool. With their expertise, they will be able to identify the root cause of the issue and find a solution to get your ABS back to functioning properly.

Check the following: if you replaced your BMW wheel speed sensor and still have a fault code for a bad ABS wheel speed sensor.

• Check wires: Check the ABS speed sensor wire in the wheel well. The wires may be accidentally pinched or exposed if the insulation is damaged. Visibly check the wire from the connector to the ABS module.
• Bad ABS Pump/Module: A defective ABS module can also cause the ABS sensor. The module is easy to replace, but the part is expensive. A cheaper solution is to remove your existing ABS module and send it for repair to a company that offers a BMW ABS wheel speed sensor.
• Sensors: Lateral, yaw rate sensors could also cause an ABS/DSC fault.
• Ground: Bad ground connection for ABS module
• Cluster: Defective instrument cluster
• Fuses/Relays: Check the ABS relay and fuse
• Brake light switch: Mounted above the brake pedal or in the master brake cylinder.
• Wheel bearing: A broken tooth on the wheel bearing can trigger BMW Brake ABS DSC lights.
• SAS: The steering angle sensor may be defective or need calibration.

ABS DTC error codes

• 5 Right Rear Wheel Speed Sensor
• 6 Right Front Wheel Speed Sensor
• 7 Front Left Wheel Speed Sensor
• 14 Solenoid Valve Relay (check fuses)
• 15 Pressure Sensor/Pump Error
• 21 Module Memory Failure – ABS/ASC module is faulty
• 23 Incorrect Coding – ABS/ASC module is faulty
• 24 Wrong Impulse
• 30 Left Rear Wheel Speed Sensor
• 31 Open Right Rear Wheel Speed Sensor
• 32 Open Right Front Wheel Speed Sensor / Wheel speed sensor, front right signal implausible
• 33 Open Left Front Wheel Speed Sensor
• 41 Steering Angle implausible
• 50 Right Front Outlet Valve – ABS/ASC module is faulty
• 51 Left Rear Outlet Valve – ABS/ASC module is faulty
• 54 Left Front Inlet Valve – ABS/ASC module is faulty
• 55 ASC Intake Valve – ABS/ASC module is faulty
• 58 Gear Box Control Unit (CAN bus error)
• 59 DMER1 (CAN bus error)
• 61 Steering Angle Sensor Identification
• 66 Speed Sensor Voltage Supply
• 67 Intermittent Interference
• 75 Engine Speed Fault from DME
• 81 Pressure Sensor
• 82 Open Yaw Rate Sensor
• 86 ASC Cut-off Valve Rear Axle
• 88 Precharge Pump
• 89 Low Voltage
• 90 Temporary System Deactivation
• 94 DDE Fault/Yaw rate sensor
• 97 Steering Angle Sensor
• 10 Brake Light Switch
• 108 SN Control
• 112 Open CAN to Instrument Cluster
• 114 Pressure Sensor Offset
• 117 Brake Light Switch Failure
• 118 DME Status-Internal Error

Frequently Asked Questions

We hope you find the BMW ABS Wheel Speed Sensor Troubleshooting guide helpful. Check these troubleshooting and repair guides for more help on your BMW.

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