What it means
The temperature sensor monitoring the electric brake booster (iBooster, eBooster) returns no usable signal. Without temperature feedback the controller derates booster assist to protect the motor.
At a glance
- Usually lights the check-engine light
How it works
Brake Booster Temperature Sensor A measures temperature at the electric brake booster so its controller can protect the booster motor and manage assist. This code sets when Sensor A's circuit does not provide a usable temperature signal, which can lead the controller to reduce assist.
Common causes
Most likely first.
- Open sensor element or broken sensor wire
- Corroded connector on the booster sensor pigtail
Symptoms
- Brake-booster warning or reduced brake assist may occur
How to diagnose it
- Scan for brake-booster and related control-module codes, then record freeze-frame data and Sensor A temperature to see when the signal becomes unusable.
- With the vehicle safely parked, check for a brake-assist warning and note whether pedal effort has changed.
- Inspect Sensor A's pigtail and connector at the electric booster for a loose fit, corrosion, or a broken wire.
- With the sensor disconnected as specified by the manufacturer, test the sensor circuit wiring for continuity and shorts.
- If the wiring and connector are sound, test Brake Booster Temperature Sensor A according to the manufacturer's procedure.
Common fixes
- Reconnect a loose Sensor A connector.
- Clean or repair corroded terminals at the booster sensor pigtail.
- Repair a broken sensor wire or damaged harness section.
- Replace Brake Booster Temperature Sensor A if it fails the manufacturer's test.
Can I keep driving?
Brake assist may be reduced, so the pedal may require more effort and stopping distances can increase. Avoid driving if braking feels abnormal or a brake warning is active; arrange diagnosis promptly and use the vehicle only if braking remains safe.
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.