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Comparing with gasoline engine, one of the worst point of diesel engine is that a lot of particle material(PM) are generated after combustion process. In order to decrease the amount of PM, CPF is equipped in EURO-4 diesel engine. CPF is the device which gathers PM with installed filter then burns it up as raising the tempt. inside of CPF above the ignition point of PM. The process which burns up PM is called "CPF regeneration".

?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.

P1405 is set when regenerating duration lasts more than 600 sec.. This code is often because normal regeneration was not performed as vehicle had driven in city centre.

Fig.1) This is the signal waveform of DPS at idle state. When CPF is new, 1.0~1.2V is outputted normally.

Fig.2) This is the waveform of DPS as accelerating.