Brake booster vacuum sensors are an electronic component found on many vehicles equipped with vacuum pumps for their brake boosters. They are usually installed in the brake booster and work to monitor the amount of vacuum present inside of the booster. They monitor the vacuum level to ensure that there is always enough vacuum present for the power brakes to operate correctly, and will set off a brake or service booster light when they detect that the vacuum has fallen below acceptable levels.
When they do fail, the computer loses an important signal as the vacuum measured by the brake booster vacuum sensor is what allows the power assisted brakes to work. Usually, a vehicle with a failed brake booster vacuum sensor will produce a few symptoms that can notify the driver of a potential problem that should be serviced.
Stiff brake pedal
One of most commonly associated symptoms of a problem with the brake booster vacuum sensor is a stiff brake pedal. A stiff brake pedal is usually caused by there not being enough vacuum present due to a problem with the brake booster vacuum pump. However, if the pedal become stiff and the brake or service booster light is not illuminated, then that means the sensor is not picking up on the low vacuum levels and may be having a problem.
Illuminated Check Engine Light
Another symptom of a problem with the brake booster vacuum sensor is an illuminated Check Engine Light. If the computer detects a problem with the brake booster vacuum sensor signal or circuit, it will set off the Check Engine Light to alert the driver that a problem has occurred. A Check Engine Light can also be set off by a variety of other problems, so it is important to have the computer scanned for trouble codes before proceeding with any repairs.
The brake booster sensor is an important piece of the braking system for vehicles equipped with brake booster pumps. They monitor an important signal for the vacuum that allows the entire power brake system to work. For this reason, if you suspect that your brake booster may be having a problem, or your Check Engine Light has come on, have the vehicle’s brake system diagnosed by a professional technician, such as one from YourMechanic. They will be able to determine if your car needs a brake booster vacuum sensor replaced, or if another repair is needed to restore functionality to your brake system.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Brake Booster Vacuum Sensor and was authored by Ed Ruelas.