P0463 on GMC: How to Diagnose & Fix
Fuel Level Sensor Circuit High Input
2 GMC models · 2 documented issues · $250-$1,100 repair
P0463 on GMC by model: symptoms, diagnosis and fix
On 2007–2014 Sierra 3500HD models, the fuel tank mounting straps and the fuel level sender unit are prone to corrosion, causing inaccurate fuel gauge readings and in some cases complete sender failure. NHTSA complaint data documents numerous owners reporting sudden fuel gauge drops to empty or erratic readings unrelated to actual fuel level. The plastic float arm on the sender can also crack, exacerbating the problem.
Common Symptoms
- Erratic or inaccurate fuel gauge readings
- Fuel gauge stuck on full or empty regardless of tank level
- Low fuel warning activating with significant fuel remaining
- Running out of fuel despite gauge showing fuel remaining
- DIC fuel range displaying incorrect distance to empty
How to Fix
Replace fuel level sender/pump module assembly (ACDelco M100087 or equivalent). Inspect and replace corroded fuel tank straps if necessary (GM part 15811919). Tank may require drop for full access. Application of anti-corrosion spray on new straps is recommended. Labor 2–3 hours; flush tank if sediment contamination is present.
Sources for this issue (1)
A very common GMT800 complaint is sulfur contamination and wear of the fuel level sensor contacts inside the tank module, causing the gauge to read empty, full, or fluctuate unpredictably. Owners often see a low-fuel warning with plenty of fuel in the tank or watch the gauge drop suddenly while driving. GM issued service information and special coverage on many trucks for this exact condition.
Common Symptoms
- fuel gauge reads empty when tank is full
- fuel gauge fluctuates while driving
- low fuel light comes on incorrectly
- distance-to-empty inaccurate
- intermittent gauge operation
How to Fix
Confirm the issue by comparing scan-tool fuel level data and observing whether the sender reading jumps erratically. The usual repair is replacement of the fuel level sensor or, more commonly, the entire fuel pump module assembly because of labor overlap and the age of the pump. Connector condition and ground integrity should also be checked during service.
Sources for this issue (1)
P0463 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0463 mean on a GMC?
P0463 stands for "Fuel Level Sensor Circuit High Input." This code means the fuel level sensor is reporting a voltage that is higher than the computer expects, which usually translates to a reading suggesting the tank is fuller than possible (such as more than full). The fuel level sensor is the float-and-sender unit inside the fuel tank that tells the gauge and computer how much fuel remains. A high-input signal points to an electrical problem like a short to voltage or an open in the sensor circuit, rather than an actual fuel issue. Besides an inaccurate or pinned fuel gauge, it can disturb EVAP system monitoring that uses fuel level data. On GMC it is documented across 2 models: Sierra 3500HD, Sierra 1500.
What are the most common causes of P0463?
The most common causes of P0463 are: Faulty fuel level sensor/sending unit (float stuck or worn), Open circuit in the fuel level sensor wiring, Short to voltage in the sensor circuit, Corroded or loose connector at the tank or sending unit, Damaged or stuck float arm inside the tank, Faulty instrument cluster or gauge driver, Faulty PCM/ECM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0463 on a GMC?
Published repair estimates on GMC range from $250 to $1,100 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0463 on a different make?
View P0463 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.