Code Definition

B2157 — Front Doppler Sensor Circuit Failure

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B2157

B2157 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B2157 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B2157 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The B2157 fault code indicates that the security or alarm control module has detected an electrical failure in the front doppler sensor circuit. Doppler sensors use a continuous ultrasonic emission and listen for frequency shifts in the reflected signal to detect movement inside the cabin, providing the volumetric intrusion detection function of the vehicle alarm system. The module sets this code when the front doppler sensor fails to respond to a self test, draws abnormal current, or returns an invalid frequency signal. When set, the volumetric intrusion detection feature is typically disable...

Join TaT to view the complete code information and diagnostic details.

Quick Facts