How to Fix P1433

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šŸšØ Diagnostic Profile

Vehicle Make: Buick

Technical Code: Fuel Level Sensor 2 Circuit High Voltage

Description: This code indicates that the Powertrain Control Module (PCM) or Body Control Module (BCM) has detected an abnormally high voltage signal coming from the secondary fuel level sensor (commonly found in saddle-style fuel tanks on Buick SUVs and Enclave models). A high voltage reading typically suggests an open circuit, a disconnected sensor, or a short to a voltage source (such as a chafed wire touching a 12V reference line).

šŸšØ Repair Difficulty Tier

Difficulty Rating: Intermediate

Summary: This repair generally requires a mid-level mechanical skill set. While replacing the sensor itself is mechanically straightforward, accessing the sensor often requires dropping the fuel tank or accessing it through a trunk floor panel. Diagnosing the circuit properly requires a multimeter and a capable OBD-II scan tool to view live sensor data (Mode $06 or live PIDs) to confirm wiring integrity versus sensor failure before parts are replaced.

šŸ› ļø Resolution Steps

Step 1: Preliminary Inspection

  • Check the vehicle’s fuel level gauge behavior; look for erratic jumping between Full and Empty or a gauge stuck on Full.
  • Inspect the wiring harness connector at the fuel pump module (located on top of the fuel tank) for corrosion, bent pins, or moisture intrusion.
  • Visually inspect the wiring harness running along the frame rail toward the rear of the vehicle for signs of chafing, pinching, or exposure to road debris that could cause a short to a reference voltage wire.

Step 2: Diagnostic Verification

  • Connect an OBD-II scan tool and navigate to live data streams to view the voltage reported by Fuel Level Sensor 2 (Secondary Sensor).
  • Disconnect the sensor harness at the fuel pump module connector. Using a multimeter, backprobe the signal wire and ground wire; a reading matching source voltage (5V) with the sensor unplugged confirms a short to voltage in the harness rather than a bad sensor.
  • If the voltage drops to 0V when disconnected but reads high when connected, this points toward an internal failure of the sending unit’s resistor card or float arm mechanism.
  • Check for proper ground integrity at the fuel pump module ground terminal to rule out a poor ground causing an elevated voltage reading.

Step 3: Resolution & Reset Process

  • If the wiring is confirmed faulty, repair or replace the damaged harness section using heat-shrink butt connectors and route it away from moving suspension components.
  • If the sensor is faulty, drop the fuel tank (or access via trunk floor access panel depending on model) and replace the secondary fuel level sending unit assembly.
  • Reconnect the battery or perform a PCM/BCM reset to clear the stored Diagnostic Trouble Code (DTC).
  • Perform a full fuel level relearn by cycling the key on/off and monitoring live data to ensure the voltage now fluctuates smoothly within the expected 0.5Vā€“4.5V range as the fuel level changes.

šŸ“¦ Parts, Labor, and Budget Estimates

Required Components/Software: Secondary Fuel Level Sending Unit, Fuel Pump Harness Repair Kit (if wiring damaged), OBD-II Scan Tool capable of live PID streaming.

Average Component Price: $45 – $120 for the sensor/sending unit; $20 – $50 for harness repair connectors.

Estimated Labor Hours: 1.5 – 3.0 hours, depending on whether the fuel tank needs to be dropped or if the sensor is accessible via an interior floor panel.