What it means
The booster temperature signal jumps or drops out for short moments. Usually a loose connector or a chafed wire that opens during vibration or thermal expansion.
At a glance
- Usually lights the check-engine light
How it works
Brake Booster Temperature Sensor A monitors temperature at the electric booster, and its signal helps the controller manage assist and protect the motor. This intermittent/erratic code sets when that signal briefly jumps or drops out rather than changing smoothly, often as a loose connector or chafed wire moves with vibration or heat.
Common causes
Most likely first.
- Sensor connector not fully seated or pin tension lost
- Harness chafed against booster housing or pedal bracket
- Connector with intermittent contact under vibration
Symptoms
- Brake-booster warning or reduced brake assist may occur
How to diagnose it
- Scan for booster-related codes and review freeze-frame data and any available Sensor A history to identify when the signal dropout occurred.
- With the vehicle safely parked, check for a brake-assist warning or pedal effort that changes during operation.
- Inspect Sensor A's connector for incomplete seating, corrosion, or terminals with poor pin tension.
- Carefully inspect the harness near the booster housing and pedal bracket for chafing, strain, or heat damage.
- Monitor Sensor A's live data while gently moving the accessible harness and connector, following the manufacturer's procedure to avoid disturbing brake components.
Common fixes
- Fully seat the Sensor A connector and secure its harness.
- Clean or repair terminals with intermittent contact or corrosion.
- Repair chafed or heat-damaged wiring near the booster or pedal bracket.
- Replace Sensor A if its signal drops out despite sound wiring and connections.
Can I keep driving?
Intermittent temperature feedback can cause the controller to reduce brake assist without warning, making the pedal harder to press and increasing stopping distance. Do not drive if assist cuts in and out or braking feels abnormal; have the fault checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.