What it means
The booster temperature signal is above the upper diagnostic threshold. Common causes are an open sensor or a short to a 5 V reference in the harness.
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 the controller can manage assist and protect the motor. This code sets when its signal rises above the allowed range, commonly because the sensor circuit is open or the signal wire is shorted to the reference supply.
Common causes
Most likely first.
- Open sensor element
- Sensor signal wire shorted to the 5 V reference
- Connector pins corroded - high contact resistance
Symptoms
- Brake-booster warning or reduced brake assist may occur
How to diagnose it
- Scan for booster-related codes and record freeze-frame data and Sensor A's live reading to establish when the high signal occurs.
- With the vehicle safely parked, check for a brake-assist warning or change in pedal effort.
- Inspect Sensor A's connector and wiring for a disconnected plug, broken wire, corrosion, or contact between the signal and reference wires.
- With the sensor disconnected as specified by the manufacturer, test the signal wire for an open circuit or short to the reference supply.
- Test Sensor A itself using the manufacturer's procedure if the wiring and connector check out.
Common fixes
- Reconnect a disconnected Sensor A plug or repair a broken wire.
- Repair a signal wire shorted to the reference supply.
- Clean or repair corroded connector terminals.
- Replace Sensor A if it is open internally.
Can I keep driving?
The controller may reduce brake assist when it cannot trust Sensor A's high reading, which can make the pedal harder to press and increase stopping distance. Avoid driving if assist is reduced or braking feels abnormal, and arrange prompt diagnosis.
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.