Power Supply Sensor Circuit Open
The vehicle's power supply sensor has a broken electrical connection, like a cut wire preventing current from flowing. The engine control module can't read the sensor signal and triggers this fault.
The ECU monitors voltage levels from the power supply sensor circuit to verify proper electrical system function. When the circuit opens, voltage signal drops to zero or becomes unreadable. The ECM detects this absence of signal as a fault condition.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 4.5-5.5 volts | Below 0.5 volts or no signal detected |
| Circuit Continuity | Complete path, low resistance | Open circuit, infinite resistance |
Code B1297 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, B1297 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.