Code Definition

B0066 — LHF seat belt pretensioner deployment loop Circuit shorted to earth or out of range

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

About B0066

B0066 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 B0066 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour.

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 B0066 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

DTC B0066 sets when the Airbag Control Module (ACM) detects a short to ground or an out of range resistance in the Left Hand Front (LHF) seat belt pretensioner deployment loop. The ACM monitors the firing loop by measuring its resistance, and a value that falls below the calibrated window, or otherwise sits outside the acceptable band, points to a short to earth or a low resistance wiring fault. The pretensioner is a pyrotechnic device that tightens and locks the driver belt at the instant of a collision, so a shorted or out of range loop compromises the ability of the ACM to control deploymen...

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