The ABS system is an additional safety feature that is now mandatory on all late model vehicles. The ABS system uses electronic sensors to detect wheel speed conditions and rapidly pulse the brakes to prevent the tires from skidding, and can rapidly stop the vehicle. The ABS system uses an electrical control module, and a series of sensors, one of which is the ABS fluid level sensor.
The ABS fluid level sensor is responsible for detecting the amount of brake fluid present in the vehicle’s brake master cylinder reservoir. This is important for the module to know because the entire braking system, as well as the ABS system operates using hydraulic brake fluid, and will not function correctly if the level falls below a certain minimum. When the ABS sensor fails, it will usually display a few symptoms that can alert the driver that there may be a problem that should be serviced.
1. The ABS Light is on
One of the first things that may happen when the ABS sensor fails is the ABS Light will come on. The ABS Light will usually come on when it is detected by the computer that the sensor has failed or is sending an incorrect signal, which may cause the ABS system to have problems. The ABS Light can also come on for a variety of other reasons so if it does become illuminated, scan the vehicle for trouble codes to reveal clues as to what the possible problem may be.
2. Unexpected wheel lock
Another symptom of a problem with the ABS fluid level sensor is a malfunctioning ABS system. Usually, the ABS system will activate automatically during heavy braking situations where wheel lock occurs. However, if the ABS fluid level sensor fails, and the level falls below a certain point, then the ABS system may not do this. This may leave the vehicle prone to unexpected wheel lock and tire skidding if the system is not functioning correctly.
3. Low fluid in reservoir
Another symptom of a failed ABS fluid level sensor is a low fluid level. This is usually indicative of two problems. One, that the fluid has somehow escaped from the system, perhaps through a leak or evaporation; and two, that the fluid level dropped and it was not picked up by the sensor. Usually, if the fluid level is low and the light has not come on, then the sensor is defective and should be replaced.
Because the ABS fluid level sensor is important to the overall functionality of the ABS system, if it fails, the problem can quickly transfer over to the rest of the system. If you suspect that your ABS fluid level sensor has failed, or your ABS Light has come on, have the vehicle diagnosed by a professional technician, such as one from YourMechanic, to determine if the vehicle needs an ABS fluid level sensor replacement, or perhaps another issue that needs to be addressed.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing ABS Fluid Level Sensor and was authored by Ed Ruelas.