Code Definition

B2172 — Inertia Switch Input Circuit Open

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

About B2172

B2172 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 B2172 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

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 B2172 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 Body Control Module (BCM) monitors the input from the Inertia Fuel Shutoff (IFS) Switch, which is a safety device designed to interrupt fuel pump power in the event of a sudden impact or rapid deceleration. DTC B2172 is set when the BCM detects an open circuit on the inertia switch input signal, meaning no electrical continuity is present on the circuit during the time the BCM expects to see the switch closed. The inertia switch is a normally closed contact that opens when triggered, so an open circuit caused by a broken wire, disconnected connector, or failed switch contacts will be detec...

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