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Have a 2006 Nissan Altima 2.5L 4 cylinder (my wife's car) that has had a problem with a P0462 fuel level sensor voltage low. I replaced the fuel pump with a new one a couple different times and still have the same issue with the fuel gauge. I have done all kinds of tests to it as well, one was a resistance check on terminals 2 and 5 with the connector to the fuel pump connected and disconnected. Even did a check before installing a new fuel pump and all checked out. I remember in one of your teaching videos about a fuel level sensor voltage high, think P0463, you mentioned also being able to check circuit integrity as well. So I undid the fuel pump connector as well recently and it had like 1.25 Volts (plugged in) and 3.8 volts (unplugged) on my scan tool data. I also had to replace a wire from the fuel pump connector going to the instrument cluster at one point too. Another test I did was use a varying resistor I have from my connector test lead kit and was able to change the resistance which in turn changed what the fuel level gauge said on the cluster (low resistance would be full, higher resistance would be empty.) I feel like it may be a bad ground or something. So what is it I seem to have missed or not understood correctly, because the P0462 code still pops up on this. Any help is appreciated. Thanks everyone.
Resistance between 2 and 5 should be 4.5 to 5.5 with the tank Full, 31.5 to 5.5 (possible typing error) and 80 to 83 when the tank is empty.
3.8 is kind of low for a 5v circuit (unplugged). You are supposed to have close to 5v with the tank empty. Did you check the ground wire for opens? A bad ground will keep the voltage high on the signal wire plugged in. Try troubleshooting the sensor as if you were troubleshooting a thermistor.
Yes I did check the resistance of the fuel pump out of the car before replacing it as well as checked the resistance while the fuel pump has been in the tank too. I had a feeling it was a bad ground or possible issue with the PCM, but if it was a PCM issue I am sure it would be not that minimal of a voltage drop of around 700 mV either. I do thank you and appreciate your reply too. I noticed using one of my potentiometers in my connector lead test kit which has 3 wires, 2 to act like a level sensor and a ground that it worked good on the fuel gauge, so I knew that the wiring and stuff was pretty good. So that's why I have been slightly stumped like what did I miss. And ScannerDanner you have helped a whole lot more than any service information too along with others. So thank you all.
I had similar issues on a '06 Altima 3.5L earlier this year. Didn't have the P0462, but the fuel level gauge would report 1/4 full when the tank was completely empty.
Couldn't find any issues with the fuel level sender or wiring. I don't recall what the open circuit level sensor signal was, exactly, but it was close to the 3.8V you found. Decided that was too low, ended up sending the instrument cluster out for repair. Came back working perfectly.
FYI, the PCM isn't directly involved in the level sensor circuit. All the magic happens between the level sender and the instrument cluster. The cluster just sends a CAN message to the PCM with the fuel level reading.
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