Seat Driver Occupied Switch Circuit Failure
The seat occupancy sensor that detects if the driver is sitting down isn't sending the correct signal to the vehicle's computer. It's like a light switch that's broken and won't reliably tell the system whether someone is actually in the seat.
The ECU monitors the driver seat occupancy switch for a valid voltage signal, typically expecting a low resistance when occupied and high resistance when empty. The system uses this signal to determine airbag deployment strategy and safety system activation. If the signal is intermittent, shorted, or open circuit, the ECU detects a circuit failure.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Seat Occupied Signal Voltage | 0.5V–4.5V (occupied) or 4.5V–5V (empty) | Out-of-range, erratic, or no signal detected |
| Circuit Resistance | <10Ω occupied / >100kΩ empty | Open circuit or short to ground detected |
Code B1515 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, B1515 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.