P1346 — Fuel Level Sensor B Circuit Malfunction

Causes

• Open or shorted wiring in the Fuel Level Sensor B circuit
• Corroded or loose connector or terminal at the fuel tank module
• Defective fuel level sensor/module (float or potentiometer)
• Poor ground or reference voltage to the sensor
• Water/contamination or mechanical binding in the sender assembly
• Faulty body/ECM input or software issue (less common)

Symptoms

• Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
• Incorrect or erratic fuel gauge readings for tank B (low, full, or fluctuating)
• Fuel level readout may be absent or inconsistent on the driver display
• Possible drivability messages or warnings for low fuel if system flags empty
• DTC stored in memory and possibly freeze frame data

What to check

• Read stored freeze frame and full DTC list with a scan tool; confirm P1346 is current
• View live data: fuel level sensor B value and compare to sensor A (if present) and instrument cluster
• Visually inspect connector and wiring to fuel tank module for damage, corrosion, or poor seals
• Wiggle test wiring while monitoring live data for intermittent changes
• Backprobe connector at the tank module and check reference voltage and ground
• Check continuity and resistance between sensor pins and ECM connector (with ignition off)

Signal parameters

• Typical sensor signal: variable voltage or resistance depending on design; many systems use ~0.5–4.5 V (empty→full) or a PWM/reflected signal — consult vehicle-specific data
• Typical resistance ranges vary by vehicle (examples: tens to a few hundred ohms). Expect a smooth, continuous change as float is moved.
• Reference voltage (if applicable): usually ~5 V or vehicle reference (check with scan tool/repair manual)
• Ground should be near 0 V with good continuity; short to battery voltage or open circuit are faults
• If module uses digital communication (LIN/CAN), expect valid bus activity; loss of bus can flag sensor circuit faults

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