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Old 04-06-2016, 04:09 PM   #1
s-h-a-w-n
Scooby Newbie
 
Member#: 433035
Join Date: Oct 2015
Chapter/Region: E. Canada
Location: Québec, Canada
Vehicle:
2012 Impreza

Default A check engine appears when I empty my tank (very low)

Hello,

My Impreza 2012 2.0 base sedan throws the code p0463 when I run the car with low fuel for an extended period of time. Example: my car sits during the day and I roll 10km a week so I often don't refuel when the computer tells me I have only 60km of fuel left (still weeks for me)

The solution: leave at least 10L of fuel in the tank at all time.

OK, but it's OK to tell my I need fuel, it's not OK to tell me the fuel sensor is in trouble. I guess the sensor reads minimum level for an extended period of time and the computer tilts, but still, it desables my traction control, stability and cruise when that happens and that's dangerous in winter.

Do you know if there is a way to get back my traction control and stability control if I leave my fuel tank low for a while (assuming I don't keep 10L in the tank)?
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Last edited by s-h-a-w-n; 04-06-2016 at 04:14 PM.
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Old 04-06-2016, 05:34 PM   #2
Rymar
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Member#: 310672
Join Date: Feb 2012
Vehicle:
2012 Impreza Ltd 5Dr
Dark Gray Metallic

Default

P0463 is "FUEL LEVEL SENSOR “A” CIRCUIT HIGH"

There are actually 2 sensors in the 2012 Impreza gas tank; they are wired in series. The ECU throws this error when:

Battery voltage >= 10.9 V
Elapsed time after starting the engine >= 3000 ms
Output voltage >= 6.533 V

Time Needed for Diagnosis:1000 ms
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.


The 2 fuel sensors both go to higher resistance as the tank gets emptier. Due to the circuitry in the display cluster, this means the voltage goes up as the tank gets emptier. It should never be above 6.533 volts, even when the tank is totally empty.

However, this condition can also be caused by an open circuit in the fuel sensor wiring.

Bottom line: this should error should NOT be happening, even if the tank is totally empty. Either one of the fuel sensors is faulty, or there is a problem with the wiring.
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Old 04-07-2016, 09:34 AM   #3
s-h-a-w-n
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Member#: 433035
Join Date: Oct 2015
Chapter/Region: E. Canada
Location: Québec, Canada
Vehicle:
2012 Impreza

Default

Thank you for this very precise answer!
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