What does it mean?
P1912 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Brake Booster Pressure Sensor Short Circuit to B+ .
Symptoms
- Malfunction indicator lamp on with a brake system or booster warning message
- Brake pedal feels harder than normal, sometimes only after several applications
- On vehicles with an electric vacuum pump, the pump runs constantly or does not run at all
- Stop-start and cruise control functions are disabled
- Idle quality can change if the module compensates for an assumed booster load
- Extra pedal effort needed for the same braking, especially at low speed manoeuvring
Likely causes
- Sensor signal wire chafed and touching a permanently powered wire near the bulkhead
- Water or corrosion inside the sensor connector bridging the signal pin to the supply pin
- Internally failed sensor pulling its own output up to supply level
- Terminal pushed out of position in the connector, contacting the neighbouring pin
- Damaged harness from a previous repair or an incorrectly routed splice
- Poor sensor ground making the signal read artificially high
- Faulty input circuit in the control module
How to fix it
- Read the freeze frame data and check the sensor value in live data with the engine off and running
- Unplug the sensor and watch the signal — if it stays high, the fault is in the harness or module, not the sensor
- Inspect the connector for water, corrosion and terminal position, and check the seal
- Trace the signal wire along the bulkhead looking for chafe against powered circuits
- Measure the sensor supply and ground at the connector and perform a voltage-drop test on the ground
- Verify with a gauge that the booster is actually holding vacuum and the check valve and hose are sound
- Repair the shorted harness section or replace the sensor; consider the module last