Technical Description of OBD-II Trouble Code
The input for the Fuel Level Sensor Circuit is registering as low.
What does that signify?
This particular diagnostic trouble code is applicable to all engines equipped with OBDII, but it is more commonly observed in certain Chrysler, GM, Ford, Lincoln, Mercury, Honda/Acura, Kia, Mazda, Mercedes Benz, Mitsubishi, Infiniti, Nissan, and Subaru vehicles.
The Fuel Level Sensor (FLS) is typically located in the fuel tank, usually at the top within the fuel pump module. The FLS converts the mechanical fuel level into an electrical signal for the Powertrain Control Module (PCM). The PCM then communicates this information to other controllers through the vehicle’s data communication bus.
The PCM uses the voltage signal from the FLS sensor to determine the amount of fuel in the tank, monitor fuel usage, and calculate fuel economy. This code is triggered if the input voltage does not match the normal operating voltages stored in the PCM’s memory. It also checks the voltage signal from the FLS sensor during the initial Key On phase.
P0462 is typically set due to electrical issues with the FLS sensor circuit. These issues should not be overlooked during the troubleshooting process, especially when dealing with intermittent problems.
The troubleshooting steps may vary depending on the manufacturer, type of FLS sensor, and wire colors.
Other related trouble codes for the fuel level sensor circuit include:
Severity & Symptoms
The severity of this issue is usually not significant. Since it is an electrical failure, the PCM can compensate for it. The compensation typically results in the fuel gauge constantly reading Empty or Full.
Symptoms of a P0462 engine code may include:
Potential Causes
The common causes for this code to be triggered are:
Diagnostic and Repair Procedures
A good starting point is to search for any technical service bulletins (TSBs) related to your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram available to address this issue, so it is worth checking before going down a potentially incorrect path.
For example, Ford products may have a TSB that covers false codes triggered by the installation of an aftermarket remote start system. This TSB should be followed to properly diagnose the condition. The TSB also covers auxiliary fuel tanks, recommending against the use of gravity feed tanks and refueling with the ignition switch in the off position for Ford trucks.
Next, locate the Fuel Level Sensor (FLS) in your vehicle. This sensor is usually mounted in the fuel tank or at the top within the fuel tank / fuel pump module. Once located, visually inspect the connector and wiring for any signs of scraping, rubbing, bare wires, burn spots, or melted plastic. Separate the connector and carefully examine the terminals inside for any signs of burning or corrosion. If cleaning of the terminals is necessary, use electrical contact cleaner and a plastic bristle brush. After cleaning, let it dry and apply electrical grease to the contact points.
If you have a scan tool, clear the diagnostic trouble codes from memory and check if the P0462 code returns. If it does not, then the issue was most likely related to the connections.
This is the most common area of concern for this code, as the fuel tank connections are prone to corrosion issues.
If the P0462 code does return, further testing of the FLS sensor and its associated circuits is necessary. With the Key Off, disconnect the electrical connector at the FLS sensor. Connect a Digital Voltmeter (DVOM) black lead to the ground or low reference terminal at the FLS sensor wiring harness connector. Connect the red lead of the Digital Voltmeter to the signal terminal at the FLS sensor wiring harness connector. Turn the Key On Engine Off and check the manufacturer’s specifications. The voltmeter should read either 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 lead of an ohmmeter to the signal terminal at the FLS sensor and the other lead to the ground or low reference terminal at the sensor. The ohmmeter reading should not be zero ohms or infinite. Refer to the manufacturer’s specifications for the resistance of the sensor to accurately test the resistance to fuel level. For example, a half tank of fuel might read 80 ohms. If the ohmmeter readings do not pass, replace the FLS.
If all previous tests have passed and the P0462 code continues to appear, it is likely that the FLS sensor has failed. However, a failed PCM cannot be ruled out until the FLS sensor has been replaced. If unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed or calibrated to the vehicle in order to be installed correctly.
