Code Definition

B0001 — PCM discrete input speed signal error

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

About B0001

B0001 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.

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 B0001 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 Powertrain Control Module (PCM) sets this code when it detects an error with the discrete input speed signal delivered to one of its hardwired input pins. This signal typically originates from a vehicle speed sensor (VSS) on the transmission tailshaft, a transmission output speed sensor, or is relayed across a dedicated wire from the ABS module or instrument cluster, rather than arriving over the CAN bus. The PCM uses this speed information to manage transmission shift scheduling, torque converter lockup, cruise control, and the speedometer output, so a missing, erratic, or implausible sig...

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