BMW 740i Wheel Speed Sensor Replacement Cost

In the event that a wheel speed sensor fails, the ABS, traction control system (TCS) and manufacturer specific stability control system lights will illuminate, informing the driver that the systems are disabled. The vehicle will be more prone to tire slip, and normal driving patterns may need to be adjusted to correct for the loss of computer control. On older vehicle's, the speedometer can be affected, causing illumination of the check engine light as well.

The vehicle can be driven with these warning lights on, since failure of the ABS or TCS does not disable the vehicle, but safety is a concern as drivers become accustomed to the road manners of their vehicle's. If hard braking that is normally controlled by the ABS control module is necessary, a collision may occur. We do recommend towing the vehicle to a repair facility if braking feels unusual under light or normal driving conditions.

Wheel speed sensors are notorious for failure, since they are housed on the wheel hub, near the road surface. This means the sensor and electrical connections are subject to dust, debris, precipitation, salt, and road hazards. Aside from that, brake dust and road grime are known to accumulate around the magnetic sensor, causing interference, and preventing proper readings. If the ABS and TCS lights are active, there is a very good chance you have a faulty wheel sensor, without regard to mileage.

Anti-lock braking systems are complex, and are typically diagnosed through professional computer scanning equipment, or manufacturer specific software. The technician will communicate with the ABS control module via computer, and view real-time data to determine what fault has been detected, and how the system is behaving. Once the technician identifies a suspected wheel speed sensor failure, physical inspection and probing will take place to ensure an accurate diagnosis. This includes inspecting the tip of the sensor for dirt and debris.

Many conditions—including corrosion, worn bearings, or other problems in ABS system—can set a wheel speed sensor trouble code. Any problem with the ABS system needs to be diagnosed before wheel speed sensors are replaced, as a new sensor may not solve the problem.

ABS wheel speed sensors can be easily damaged during other repairs that call for the wheels to be removed (especially brake work). If you have had recent repair work performed, return the vehicle to the shop to inspect for damage.