P2066 — Fuel level sensor B is not working properly

The code indicates a problem with the second fuel level sensor in the tank. It means the sensor's readings are inconsistent or out of expected range, causing the engine control unit to flag it. This sensor helps the car accurately measure fuel level, so issues can affect fuel gauge accuracy or trigger warning lights.

Common causes

The cause is almost always one of a few things. Here they are — P2066 rarely comes from anything outside this list:

• Faulty or damaged fuel level sensor B
• Wiring issues or poor electrical connections
• Corroded or dirty sensor contacts
• Fuel tank contamination or debris
• Faulty fuel pump module housing the sensor

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Check and clean sensor electrical connections
2. Inspect wiring harness for damage or corrosion
3. Test sensor resistance and signal output
4. Replace faulty fuel level sensor B if needed
5. Replace fuel pump module if sensor is integrated

That is what holds for P2066 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.