P2068 - FUEL LEVEL SENSOR "B" CIRCUIT HIGH

This DTC is a generic transmission code, indicating that it is applicable to OBDII-enabled vehicles. Although it generally follows particular repair steps, it can also differ depending on the brand or model of your car. But we’ll talk about that later, for now, let’s focus on understanding how it works.

The Fuel Level Sensor (FLS), is placed in the fuel tank, generally an integral part of the fuel pump module. It usually is not replaceable without changing the fuel pump module, although there are some exceptions. Connected to the tank arm is a floater that moves over a resistor that is either grounded to the tank. The voltage is supplied to the sensor and the path to the ground, which shifts as the fuel level increases. The voltage quantity will vary depending on the system, but 5 volts is not unusual.

When the fuel level changes, the float moves the arm, and the resistor switches to the ground, resulting in a variation of the voltage signal. Depending on the system, this signal may be transmitted to a control module or directly to the instrument cluster. If the fuel level signal being sent to the PCM (Powertrain Control Module) is above 5 volts for a certain amount of time, DTC P2068 OBD2 is set. Check with your vehicle’s information source for the FLS Sensor “B” circuit.

• Check Engine light illuminated.
• The fuel light may come on.
• Abnormal fuel level gauge changes.

The factors for which the P2068 OBDII fault code is set are:

• Maybe the signal circuit to the fuel sender is open or shorted.
• Perhaps the ground circuit is open.
• The fuel tank could have been damaged resulting in problems with the fuel level circuit.
• Possibly the Fuel Level Sensor is defective.
• The instrument cluster possibly has defects.

To troubleshoot the P2068 OBD2 diagnostic code you must do the following:

• Inspect the fuel tank along with all the cables related to the fuel tank. Check if the tank shows any damage due to knocks, which may have affected the fuel pump. Also, check that the ground signal is well grounded and that the wires are in good condition for proper operation. Repair it as required.
• Perform a voltage drop test on the ground circuit to determine if there is high resistance in the ground circuit. To do this use a voltmeter connected to both the battery ground and the FLS sensor ground. You should obtain a value of fewer than 0.1 volts. In case there is 1 volt or close to that value, it requires repairing the sensor ground signal.
• If after verifying that there is a good ground supply to the Fuel Level Sensor circuit, you must replace the sensor.

As we mentioned above, the easiest method of testing the fuel level circuit is to verify that the FLS is correctly wired to the ground at the fuel tank connector. You can do it with a wrench on the fuel gauge, it should go to one end or the other. Removing the ground path completely should result in the opposite behavior of the gauge. If the sensor activates, you know that the wiring supplying voltage and ground to the fuel level sensor is okay and that the instrument cluster is most likely all right.

So keep in mind that the prime suspect is the fuel level sensor itself. It may be necessary to remove the fuel tank to access the fuel pump module in the tank. Although a PCM or BCM (Body Control Module) failure is not out of the question, it is highly implausible. Don't assume this is the origin of the fault code in the first place. At any rate, it is advisable to go to the nearest mechanic in your area in case you do not know how to detect and solve this problem by yourself.