ALl of the above are relevant. It would have been interesting to have the code read .
THe pressure sensor connector is accessible from the trap under the rear seat. this sensor is analog
From the shop manual available at
www.kiatechinfo.com : (test is made witn connector installed and engine running. )
4. Using a voltmeter, measure voltage at all three Fuel Tank Pressure Sensor terminals in the fuel tank sending unit connector.
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WHT/BLK - 2.0 - 3.0 V (signal return voltage/base reading)
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If signal voltage reads 5.0 volts, check the sensor ground wire.
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GRN/YEL - 0.0 V (sensor ground)
YEL/GRN - 5.0 V (reference Voltage)