OBD-II code B0090 indicates a fault with the left frontal restraints sensor, which is part of the vehicle's airbag and seat‑belt pretensioner system. The sensor monitors crash severity on the driver‑side front; when its circuit is open, shorted, or the sensor itself fails, the airbag control module sets this code and illuminates the airbag warning light.
The sensor itself may be internally damaged or have drifted out of specification, causing an open or short circuit that the control module detects.
Wires leading to the left frontal sensor can suffer abrasion, chafing, or corrosion, especially where they pass through the front bulkhead or near moving components.
The sensor’s electrical connector may have corroded terminals, bent pins, or insufficient seating, leading to intermittent or permanent signal loss.
Less commonly, a fault inside the SRS control module (e.g., a failed driver‑side sensor input circuit) can trigger B0090 even when the sensor and wiring are intact.
The powertrain control module does not directly manage the left frontal restraints sensor; a PCM fault would only be plausible if it inadvertently disables power or ground to the SRS system, which is uncommon.
No. The PCM does not control the left frontal restraints sensor, and replacing it rarely resolves B0090. Focus first on the sensor, its wiring, connectors, and the airbag control module.
Driving is possible, but the driver‑side front airbag and pretensioner may not function correctly in a crash, increasing injury risk. The fault should be diagnosed and repaired promptly.
Clearing the code only turns off the warning light; if the underlying fault remains, the light will return and the airbag system may still be disabled.