P2066 OBD-II Trouble Code: Fuel Level Sensor “B” Performance

P2066 code definition

Fuel Level Sensor “B” Performance

What the P2066 code means

P2066 is an OBD-II generic code for the engine control module (ECM) detecting the fuel level sensor “B” performance. The sensor output voltage is not accurate when compared to the fuel level sensor “A”.

What causes the P2066 code?

• The engine control module (ECM) uses fuel level sensors A and B output voltages to determine the vehicle's fuel control. The two fuel senders are used on vehicles that have a dual bladder or a dual sump fuel tank.

• The sensor does not move indicating the fuel is going down after a certain amount of miles are driven. (e.g., it is after 100km or 62 miles for a Chevrolet)

• There is a difference between the two sensors of about 7 gallons after about 200 km or 120 miles are driven, or for more than 30 minutes of driving.

What are the symptoms of the P2066 code?

• The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

• The fuel system may not reflect how much fuel is in the fuel tank.

• The vehicle may run out of fuel if the fuel tank sensor is not accurate.

How does a mechanic diagnose the P2066 code?

• Scans for codes and documents any codes in the ECM, and then looks at the freeze frame data for failure.

• Checks the sensor A and B to compare the readings for fuel level and compares it to the actual fuel level.

• Checks the fuel level sensor B for the proper resistance with a multimeter.

• Follows the manufacturer pinpoint tests for the diagnosis and replacement of the fuel level sensor B.

Common mistakes when diagnosing the P2066 code?

• Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

• Failing to clear the ECM codes after the codes are fixed so the ECM will enable the system to be normal again.

• Replacing the fuel level sensor without first checking the fuel transfer pump is working to transfer the fuel from one side to another if vehicle is equipped.

How serious is the P2066 code?

• Code P2066 is a code letting the operator know the fuel level sensor is not working properly and may affect the amount of fuel available to the engine.

What repairs can fix the P2066 code?

• Replacing the fuel pump sending unit B
• Repairing the connector pins of corrosion or loose connections at the fuel pump or the fuel tank

Additional comments for consideration regarding the P2066 code

Code P2066 is for a performance problem with the fuel level sensor B. Vehicles that use this second sensor may also have a transfer pump that may be failing and will cause the unequal fuel levels in the two sides of the fuel tank. Keep this in mind when diagnosing the code and look at other codes that may also be present.

Need help with a P2066 code?

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