Severity and Symptoms
Severity depends on the failure. In case of mechanical failure; severe. In case of electrical failure, less severe, which the PCM can compensate for. Compensation typically means the fuel gauge reads empty or full all the time.
Symptoms of an engine code P2065 may include:
- Malfunction Indicator Lamp (MIL) illuminated
- Perceived decrease in fuel economy
- Reduced distance to empty mileage
- Incorrect fuel level on the gauge in the instrument cluster – always reads incorrectly
Potential Causes
Typically, the causes for this code to set are:
- Open in the signal circuit to the FLS sensor – possible
- Short to voltage in the signal circuit to the FLS sensor – possible
- Short to ground in the signal circuit to the FLS sensor – possible
- Failed FLS sensor/sensing arm mechanically stuck – probable
- Failed PCM – unlikely
Diagnostic and Repair Procedures
A good starting point is always to search for a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogramming to address this issue, and it’s worth checking before discovering you’ve taken a long/wrong path.
A good example of this is on Ford products where an aftermarket remote start system was installed. This can cause a false code to set. There is a TSB covering this topic and it should be followed to properly diagnose this condition. Auxiliary fuel tanks are also covered in this TSB. Gravity-feed tanks are not recommended for use on these systems and when refueling Ford trucks. It is recommended to fill the main tanks with the ignition switch in the off position.
Next, locate the Fuel Level Sensor (FLS) on your specific vehicle. This sensor is typically mounted in the fuel tank or may even be on top of the fuel tank module/fuel pump. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they appear burned or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if terminal cleaning is necessary. Let it dry and apply electrical grease where the terminals make contact.
If you have a scan tool, clear the diagnostic codes from memory and see if the P2065 code returns. If not, the connections were likely your problem.
This is the most common area of concern for this code, as fuel tank connections have the highest number of corrosion issues.
If the P2065 code returns, we will need to test the FLS sensor and its associated circuits. With the key off, disconnect the electrical connector from the FLS sensor. Connect a black wire from the Digital Volt Ohm Meter (DVOM) to the ground or low reference terminal at the FLS sensor wiring harness connector. Connect the red wire from the DVOM to the signal terminal at the FLS sensor wiring harness connector. Turn the key to the engine off position. Check manufacturer specifications; the voltmeter should read 12 volts or 5 volts. If the voltage is incorrect, repair the power or ground wire or replace the PCM.
If the previous test passed, connect one wire of an ohmmeter to the sensor’s signal terminal and the other wire to the sensor’s ground or low reference terminal. The ohmmeter reading should not be zero ohms nor infinite. Check manufacturer specifications for sensor resistance to accurately test resistance at fuel level (1/2 tank of fuel may read 80 ohms). If the ohmmeter readings fail, replace the FLS.
If all previous tests passed and you continue to get a P2065, this would most likely indicate a faulty FLS sensor, although a faulty PCM cannot be ruled out until the FLS sensor has been replaced. When in doubt, seek assistance from a qualified automotive diagnostician. PCMs must be programmed or calibrated to the vehicle to be installed properly.