Air Bag Crash Sensor #2 Ground Circuit Open
The airbag control module can't properly communicate with crash sensor #2 because its ground wire is broken or disconnected, like a light switch with a severed return path to the electrical panel. Without a solid ground connection, the sensor can't send reliable signals to deploy the airbag in a crash.
The airbag ECU monitors the ground circuit voltage and resistance of crash sensor #2 during key-on self-test. It expects near-zero resistance to ground and will detect an open circuit (infinite resistance) as a fault. The system continuously verifies this path to ensure crash detection capability.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Ground Circuit Resistance | < 1 ohm | > 10 ohms or open circuit |
| Ground Voltage Drop | 0.0-0.5V | > 1.0V |
Code B1945 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, B1945 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.