Boost Pressure Sensor(BPS) is installed in intake manifold and senses the pressure of air inside of intake manifold which is compressed by turbo charager.

Measuring mass air flow accurately with the information of intake mainfold pressure, mass air flow and intake air temperature, ECM performs actuating correction of EGR and VGT.

When excessive intake manifold pressure is detected, engine power generation is limited to protect engine because too highly compressed pressure due to turbo charger may harm engine.

P0069 is set when the difference between Boost pressure and atmospheric pressure sensor is above 300hpa at below 100RPM (in other word, IG key ON condition) for more than 3 sec. This code is due to abnormal output characteristic of BPS component.

Fig.1) The waveform of BPS signal as accelerating from idle state. Signal voltage rises as accelerating.