What it means
The signals of fuel level sensors A and B do not correlate within the calibrated tolerance. Common in saddle tanks where two sensors monitor each tank half.
At a glance
- Usually lights the check-engine light
How it works
Fuel level sensors A and B measure fuel in separate areas of the tank, often the two sides of a saddle tank. The control module compares their readings, and this code sets when the signals disagree beyond the calibrated tolerance, as can happen with a stuck float or failed transfer pump.
Common causes
Most likely first.
- One float stuck on guide rod
- Saddle tank transfer pump failed
Symptoms
- Check-engine light
- Fuel gauge reading inaccurately or fluctuating
- Incorrect low-fuel warning or reduced driving range estimate
How to diagnose it
- Record freeze-frame data and compare live fuel level sensor A and B readings, noting whether the disagreement changes as fuel is used.
- Check the fuel gauge and low-fuel warning against the actual fuel level to establish how the mismatch affects the displayed range.
- Inspect accessible wiring and connectors for both fuel level sensors for damage, loose connections, or corrosion.
- With appropriate precautions for fuel-system work, check whether each sensor's reading changes smoothly through the manufacturer's specified test.
- If the readings diverge in a saddle tank, test the transfer pump and inspect each float for binding on its guide.
Common fixes
- Repair a loose or damaged connector or wiring at the affected fuel level sensor.
- Free or replace a float that is stuck on its guide rod.
- Replace the fuel level sensor that fails its specified movement or electrical test.
- Repair or replace the saddle tank transfer pump if testing confirms it is not moving fuel between tank sections.
Can I keep driving?
You can generally continue driving if the vehicle runs normally, but do not rely on the gauge, low-fuel warning, or range estimate until repaired. Keep extra fuel in reserve to avoid running out unexpectedly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.