B0053 indicates a fault in the second-row left seat-belt sensor circuit, which reports buckle status to the supplemental restraint or occupant-detection system. The code can be set by an open, short, or out-of-range signal from the buckle switch or its wiring. It typically turns on the airbag/SRS warning lamp and may affect restraint-system logic.
The internal switch that detects buckle/unbuckle is the component most directly involved and is the statistically most common cause of this code.
Loose terminals, moisture intrusion, or oxidation in the sensor connector can interrupt the signal and set the fault.
Seat movement and foot traffic commonly fatigue the harness running to the buckle, causing opens or shorts to ground/power.
A coin, spill residue, or other obstruction can prevent proper latch engagement and confuse the sensor reading.
If the sensor, connector, and wiring all test normal, an internal module input failure is possible but is the least likely cause.
The vehicle will usually drive normally, but the airbag/SRS system may not operate as intended, so it should be diagnosed promptly.
Often yes, because the sensor/switch is integral to the buckle; repair depends on whether the manufacturer allows separate sensor service.
Usually no. The sensor, its connector, or the wiring is far more commonly at fault. Module replacement should only be considered after those items are ruled out.
A scan tool can clear the code, but it will return if the underlying circuit or sensor fault has not been corrected.