🚨 Diagnostic Profile
Vehicle Make: Buick
Technical Description: Fuel Level Sensor 2 Circuit Low Voltage
This diagnostic trouble code indicates that the Powertrain Control Module (PCM) or Body Control Module (BCM) has detected a voltage reading from the secondary fuel level sensor circuit that falls below the acceptable calibrated threshold. Many Buick models equipped with saddle-style fuel tanks use two sensors (Sensor 1 and Sensor 2) to accurately measure fuel level across both sides of the tank. A ‘Low Voltage’ fault typically points to a short to ground, a corroded connector, a failing sensor float arm, or an open circuit in the wiring harness feeding the secondary sending unit.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires the use of a digital multimeter to test resistance and voltage drop across the sensor circuit, along with a capable OBD-II scan tool to view live sensor data (PIDs). While the diagnostic process requires moderate electrical knowledge, the physical repair often involves fuel tank access, which requires proper safety precautions (fuel system depressurization) but does not typically require dealer-level module programming unless the BCM itself requires reprogramming or relearning after a module replacement.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the fuel pump module electrical connector located on top of the fuel tank, as corrosion or loose pins are a common culprit. Check the wiring harness that runs from the connector back to the BCM/PCM for any signs of chafing, pinching, or exposure to rust/salt (common in trunk floor pass-throughs on sedans). Inspect the ground strap connections near the fuel tank straps, as a poor chassis ground can mimic a ‘low voltage’ sensor fault.
Step 2: Diagnostic Verification
Connect an OBD-II scan tool and navigate to live data streams to monitor the ‘Fuel Level Sensor 2’ voltage while manipulating the sensor (if accessible) or while simulating fuel level changes. Using a digital multimeter with the key in the ‘ON’ engine ‘OFF’ position, back-probe the signal wire at the fuel pump connector to check for the presence of a 5-volt reference signal from the BCM. If the reference voltage is missing, the issue lies upstream in the wiring or module; if present but the return signal is near 0V constantly, the sensor itself has likely failed internally or shorted to ground.
Step 3: Resolution & Reset Process
If the wiring and connectors test positive (no corrosion, proper continuity, and correct reference voltage), the fuel level sensor assembly (often integrated into the sending unit) will need to be replaced. After replacing the sensor, clear the Diagnostic Trouble Codes (DTCs) using the scan tool. Cycle the ignition key to the ‘ON’ position without starting the engine for 30 seconds to allow the BCM to re-initialize the circuit, then start the vehicle and verify the fuel gauge responds correctly and no codes return after a drive cycle.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Fuel Level Sensor (Sending Unit), Electrical Connector Pigtail (if wiring damaged), Digital Multimeter, OBD-II Scan Tool.
Average Component Price: $45 – $150 for the sensor/sending unit assembly, depending on whether it is purchased as a standalone sensor or a full fuel pump module assembly.
Estimated Labor Hours: 1.5 to 3.5 hours, which includes fuel tank drop/access time if the sensor is not accessible without removing the tank.