What it means
The booster temperature sensor reading is implausible relative to commanded assist or coolant temperature. The signal moves too slowly, sticks, or never reaches expected values during operation.
At a glance
- Usually lights the check-engine light
How it works
Brake Booster Temperature Sensor A reports the temperature of the electric booster motor area so the controller can manage assist and protect the motor. This range/performance code sets when the reading is implausible or changes too slowly relative to operating conditions, even though a signal is present.
Common causes
Most likely first.
- Sensor drift or contamination on the temperature element
- Sensor not seated properly against the booster motor housing
- Sensor element aged beyond calibration window
Symptoms
- Brake-booster warning or reduced brake assist may occur
How to diagnose it
- Scan for booster-related codes and record freeze-frame data, including Sensor A temperature and commanded assist, to identify the conditions behind the implausible reading.
- Compare Sensor A's live temperature trend from a cold start through booster operation with other available temperature data for an implausible or stuck value.
- Inspect Sensor A's mounting and contact with the booster motor housing to see whether it is seated as intended.
- Inspect the sensor element, connector, and nearby wiring for contamination, damage, or corrosion.
- If the sensor is seated and wiring is sound, test Sensor A's response using the manufacturer's procedure.
Common fixes
- Seat Brake Booster Temperature Sensor A correctly against its specified mounting point.
- Clean or repair corroded sensor connector terminals.
- Repair damaged sensor wiring or harness insulation.
- Replace Sensor A if it drifts or responds too slowly in the manufacturer's test.
Can I keep driving?
A faulty temperature reading may cause the booster controller to reduce assist, increasing pedal effort and potentially stopping distance. Avoid driving if brake assist feels reduced or inconsistent, and have the system 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.