P2066: Fuel Level Sensor B Performance

P2066 flags a second fuel level sender whose reading is electrically valid but does not behave like real fuel. Makers test it differently. GM, on dual-tank trucks with an electric transfer pump, calls it Fuel Level Sensor 2 Performance and looks for a secondary reading that stays frozen while the engine burns 18 L or more, or that barely moves while the pump transfers fuel; Type B, two trips. Ford instead files a noisy signal here: more than 100 jumps of over 40 % between samples taken every 0.1 s, while a stuck sender B gets P25B1. Genesis compares calculated fuel use with the change the sender reports and revised that logic for the 2025 GV80 (25-01-026G). Jeep released PCM flashes for P2066 on 2021–2024 Grand Cherokee models, one symptom being a MIL after refuelling with the engine running. Mercedes uses P206600/P206609.

Symptoms

• Fuel gauge stays put or lags behind real consumption
• MIL after refuelling or long drives
• Range display and low fuel warning unreliable

Most likely causes

• Float arm sticking or sender card worn in one spot
• Transfer or jet pump not moving fuel between tank halves
• Plausibility logic needing a software update (Jeep, Genesis)
• Poor contact causing a noisy signal (Ford definition)

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and wiring
2. Compare the reading with other engine data while varying the engine speed.
3. Use live data to compare the reading with actual conditions
4. Measure power, ground, and signal
5. Replace the sensor if the circuit is good

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P2066 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 0: Subsystem depends on the code range
• 66: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2066?

You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

What causes code P2066?

The most common causes are: float arm sticking or sender card worn in one spot; transfer or jet pump not moving fuel between tank halves; plausibility logic needing a software update (Jeep, Genesis).

Related codes

• P2065Fuel Level Sensor B Circuit
• P2067Fuel Level Sensor B Circuit Low
• P2068Fuel Level Sensor B Circuit High
• P0461Fuel Level Sensor A Circuit Range/Performance
• P25B1Fuel Level Sensor B Stuck
• P2636Fuel Pump B Low Flow/Performance

Sources

• gsi.ext.gm.com: 20OBDG04 Diagnostics
• fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001
• static.nhtsa.gov: MC 11018881 0001
• static.nhtsa.gov: MC 11006977 0001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.