What it means
Secondary fuel-level sensor B reads within range but plausibility check fails — value sticks, jumps, or does not match consumption.
How it works
Fuel level sensor B is the secondary sender used on some vehicles to measure fuel in a saddle tank or auxiliary tank. The control module checks whether its reading changes plausibly as fuel is used and whether it agrees with the expected tank level. P2066 sets when sensor B's signal is electrically plausible but behaves inconsistently, such as sticking or jumping.
Common causes
Most likely first.
- Fuel sender float or arm sticking
- Worn or erratic sender resistor
- Loose or corroded sender connection
Symptoms
- Check-engine light
- Fuel gauge may stick or move erratically
- Fuel-level reading may not match fuel use
- Low-fuel warning may come on at the wrong time
How to diagnose it
- Record freeze-frame data and check for related sender codes to see whether sensor B's reading changed abruptly or stopped tracking fuel use.
- Compare sensor B scan-tool data with the primary sender, fuel gauge and known fuel level, if the vehicle exposes these readings.
- Inspect the sensor B connector and accessible wiring for looseness, corrosion or intermittent contact.
- Observe the sensor B reading as fuel level changes, or use the manufacturer's test procedure to check for a sticking float or erratic sender resistance.
- If the sender signal is stable at the component but not at the module, test the harness and connections for intermittent resistance.
Common fixes
- Clean and secure a loose or corroded sensor B connection.
- Repair an intermittent wire or connector fault in the secondary sender circuit.
- Replace a sender with a sticking float or arm.
- Replace sensor B if its output remains erratic during testing.
Can I keep driving?
The vehicle is generally safe to drive, but the fuel gauge may stick or misstate how much fuel remains. Refuel early and avoid relying on the low-fuel warning until the sender is repaired.
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.