Fuel Level Sensor B Circuit Malfunction
Your car's backup fuel level sensor (the secondary gauge sender) isn't communicating properly with the engine computer, like a broken radio that won't send its message. The ECU can't read the fuel tank level from this sensor circuit, which may affect fuel pump operation or gauge accuracy.
The ECU monitors the voltage signal from fuel level sensor B (typically a variable resistor that changes resistance as the float moves). It expects a smooth voltage range that correlates to tank fullness. If the voltage is out of range, shorted, or open-circuit, the ECU triggers this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor voltage | 0.5V to 4.5V (proportional to fuel level) | Below 0.1V or above 4.9V, open circuit, or erratic signal |
| Signal response time | Smooth, gradual voltage change | Rapid spikes, no change, or stuck value |
Code P1351 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, P1351 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.