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Differential pressure sensor(DPS) is piezzo electric type sensor. Sensing the differential pressure between in front of CPF and in the back of CPF, DPS outputs linear signal from 0~5V. Using output signal, DPS detects the amount of soot, sulfide, SOF(soluble organic fraction) to determine if CPF regeneration is needed.

?CPF regeneration?When vehicle is in steady speed condition and above normal engine loading condition, if differential pressure between before and after CPF is above the specified pressure, ECM considers that stored soot inside of CPF is excessive. In this condition, exhaust gas tempt. is raised by post injection 1 and 2 to warm CPF up to 550?~650?. In this high tempt, soot inside of CPF burns up naturally and this mechanism is called as "CPF regeneration". Most of soot is burned up during regeneration process but a little amount of soot is not burned up and stored inside of CPF continuously. The stored soot decreases the efficiency of CPF slowly. DPS corrects CPF regeneration period and duration as comparing and calculating the differential pressure due to stored soot with the total distance covered.

P0471 is set when the measured Differential pressure is above 100 hPa - the upper limiting value - for more than 1 sec. This code is due to 1) short beween power and signal circuit or 2) short to battery in signal circuit or 3) short to ground in ground circuit.