Power Supply Sensor Circuit Short To Battery
A sensor that monitors power supply voltage is detecting a short circuit directly to the battery's positive terminal, like a wire touching the wrong connection. The ECU sees excessive voltage when it should see a controlled signal.
The ECU monitors a power supply sensor's output voltage through a pull-down resistor circuit. When the sensor functions normally, voltage stays within a safe range. A short to battery means the signal wire is directly connected to positive voltage, causing the ECU to read maximum voltage continuously.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Signal Voltage | 0.5V to 4.5V (variable based on supply) | Greater than 4.8V or stuck at battery voltage |
| Circuit Resistance | Expected pull-down resistance path intact | Zero or near-zero resistance to battery positive |
Code B1298 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, B1298 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.