Passenger Side
The passenger side airbag system has detected a fault in its circuit or sensor, similar to a smoke detector with a dead battery that can't alert you to danger. This code indicates the airbag control module cannot properly monitor or deploy the passenger airbag if needed.
The airbag control module monitors the passenger side airbag circuit continuity, sensor resistance, and deployment readiness. It detects open circuits, short circuits, or sensor failures by measuring voltage and resistance values against known thresholds. If readings fall outside safe parameters, the fault code is triggered and the airbag is disabled for safety.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Airbag circuit resistance | 2-10 ohms | >100 ohms or open circuit |
| Occupancy sensor voltage | 0.5-4.5V | <0.2V or >4.8V |
Code B1999 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, B1999 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.