Air Bag Crash Sensor #2 Ground Circuit Short To Battery
The airbag crash sensor #2's ground wire is shorted directly to battery power instead of being properly grounded, like a light switch that's stuck in the 'on' position. The airbag control module detected this abnormal voltage condition and set a fault code.
The airbag ECU monitors the ground circuit voltage of crash sensor #2, expecting it to be at or near 0V (true ground potential). When the circuit shorts to battery voltage (typically 12V+), the ECU detects this abnormal voltage level and triggers the fault code. The sensor cannot function properly because the ground reference is compromised.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Ground Circuit Voltage | 0V to 0.5V | Above 2V (shorted to battery) |
| Circuit Resistance to Ground | Less than 5 ohms | Very high resistance or open circuit |
Code B1908 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, B1908 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.