Q: How to check and replace the fuel tank pressure sensor in Chevrolet Tracker?
A: The fuel pressure sensor, part of the EVAP control on OBD-11 vehicles, detects vapor pressure in the fuel tank. Located atop the tank, it opens the tank pressure valve when a certain pressure is met. If malfunctioning, it signals the PCM, causing a diagnostic trouble code. To test, remove the sensor, connect it to three 1.5V batteries in series, and expect around 2.5 volts between "Vout" and Ground. A vacuum/pressure pump can verify voltage changes with varying pressure. If faulty, replace the sensor. During replacement, inspect for clogs, check the O-ring, and tighten bolts to the specified torque.