The code Po106 is defined as "Baro Circuit fault." The barometric pressure on this vehicle is calculated via the EGR boost sensor. The items that can be at fault include:
EGR Boost Sensor, EGR Boost Sensor Solinoid, Vacumme lines, and the PCM (Powertrain Control Module or engine computer)
The first check you want to make is the vacumme lines for the EGR system, make sure none are cracked, broken, swollen, sucked in, or wethered; even if they visually look good they may be plugged inside. The rest of the system has to be properly diagnosed in order to correctly determine if the boost sensor, soilinoid, or PCM has malfunctioned. But if you do find a bad hose the Check Engine Lamp has to be reset in order to see if the repair took. The Sensor and Soilinoid also fail commonly on higher milage vehicles and would be the next step in replacing if you opt not to have the vehicle diagnosed by a repair facility. The wiring to the sensor, and the computer itself rarely fail, but are always a possibility unless properly tested.