Sensor Power Supply High Input
The ECU detected that a sensor's power supply voltage is too high, like a battery charger stuck on maximum output. This means the sensor isn't getting the right amount of electrical power, causing the ECU to distrust its readings.
The ECU monitors the reference voltage supplied to various sensors (typically 5V). When this supply voltage exceeds safe limits, the ECU recognizes that sensor data is unreliable. The fault triggers when the power supply rail voltage climbs above the maximum threshold, indicating a voltage regulator failure or wiring short.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Reference Voltage | 4.8V - 5.2V | >5.5V or shorted high |
| Regulator Output | 5.0V ±0.1V | Exceeds 5.5V sustained |
Code P1247 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1247 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.