Longitudinal Acceleration Threshold Exceeded
Your vehicle's acceleration sensor detected a sudden, extreme change in forward/backward motion that exceeded safe limits. Think of it like a seatbelt pretensioner triggering when the car jerks too hard—the system is flagging an abnormal movement event.
The ECU monitors longitudinal acceleration via accelerometers or inertial sensors to detect crash conditions and control stability systems. When acceleration exceeds a calibrated threshold (typically 0.5–1.0 g), the system triggers safety responses. A fault occurs when sensor data spikes abnormally or wiring is compromised.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Longitudinal Acceleration | −0.5 to +0.5 g under normal driving | >1.0 g sustained or erratic spikes |
| Sensor Signal Voltage | 0.5–4.5 V | <0.2 V or >4.8 V |
Code B1231 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, B1231 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.