P1348: Fuel Level Sensor B Circuit Low

P1348 is a powertrain code indicating that the ECU or PCM has detected an abnormally low voltage signal on the Fuel Level Sensor B circuit. On vehicles with dual fuel level sensors, such as those with saddle-type tanks or secondary tank monitoring, Sensor B refers to the secondary sensor in the circuit. The PCM monitors the signal voltage from this sensor to track fuel quantity and feed that data to the gauge and fuel management logic. When the signal drops below the expected low-end threshold, P1348 is stored.

A low circuit condition is typically caused by a short to ground in the signal wire, a failed sensor with a shorted element, a corroded connector pulling the circuit voltage down, or, less commonly, a fault in the PCM's sensor input circuit. Check the sensor connector and the harness run for signs of chafing, moisture ingress, or corrosion. Testing the signal voltage at the connector with a multimeter will quickly confirm whether the sensor is producing a signal at all, and whether disconnecting it removes the low voltage condition, pointing to a wiring fault versus the sensor itself.

At medium severity, P1348 primarily affects fuel level accuracy rather than drivability, but inaccurate fuel level data can influence other fuel management calculations depending on the vehicle. It will not cause immediate mechanical harm, but an unreliable fuel level reading is a practical problem. Address it at your next service or sooner if your fuel gauge behaviour is noticeably wrong.