Air Bag Crash Sensor #2 Ground Circuit Failure
The airbag system's crash sensor #2 has lost its ground connection, like an electrical wire coming unplugged from the battery's negative terminal. The airbag control module can't properly detect crash signals because the sensor circuit is incomplete.
The ECU monitors the ground circuit continuity of crash sensor #2 by measuring resistance and voltage drop across the sensor's ground path. When the ground circuit fails, resistance becomes abnormally high or infinite, triggering a fault code. The module expects a solid ground connection with minimal resistance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Ground Circuit Resistance | < 1 ohm | > 10 ohms or open circuit |
| Sensor Ground Voltage Drop | 0-0.1V | > 0.5V |
Code B1907 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1907 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.