Seat Driver Occupied Input Circuit Open
The car's seat occupancy sensor isn't sending a signal to the computer, like a light switch with a broken wire. The ECU can't detect whether someone is sitting in the driver's seat.
The ECU monitors the driver seat occupancy switch for a valid signal voltage when the ignition is on. This sensor tells the airbag control module whether to arm the airbag system. An open circuit means the expected voltage signal is never detected.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Seat Occupancy Signal Voltage | 4.5-5.5V (closed switch) or 0V (open switch with valid transition) | No voltage transition or stuck signal for >2 seconds |
| Circuit Resistance | < 10 ohms (closed) or > 1M ohm (open) | Open circuit (infinite resistance) detected |
Code B1673 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, B1673 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.