Description
OBD-II Trouble Code Description for P0478 Seat
Exhaust Pressure Control Valve High
What does this mean?
OBD2 Code P0478 Seat definition:
Exhaust Back Pressure Regulator – Is a variable position valve that controls exhaust back pressure during cold ambient temperatures to increase cab heat and decrease the amount of time needed to defrost the windshield. The PCM uses the measured exhaust back pressure, (ambient) intake air temperature, engine oil temperature and engine load to determine the desired exhaust back pressure. Valve position is controlled by switching the output signal circuit to 12 volts inside the PCM. On/off time is modulated from 0 to 99 % dependent upon the exhaust back pressure desired. Upon each initial engine start-up, the PCM exercises the exhaust back pressure valve by commanding it to cycle on and off once. If upon start-up the temperature of intake air sensed by the IAT sensor is < 37¡ãF (5¡ãC) and the oil temperature sensed by the EOT sensor is between 32¡ã-140¡ãF (0-60¡ãC) it will continue to keep the back pressure valve partially closed. As the oil temperature rises during engine operation, the PCM will control the valve in response to the rising oil temperature.
Symptoms
Possible sumptoms of OBD code P0478 Seat
– Engine Light ON (or Service Engine Soon Warning Light)
Causes
Possible causes of OBD code P0478 Seat
– Exhaust Back Pressure Valve The Error code is generally activated on detection of the following conditions: An open or shorted to ground control circuit can be detected by an on demand output circuit check performed during the engine off test. Problems with either the Exhaust Back Pressure Device or the tube between the exhaust manifold and the EBP sensor can be detected during the exhaust back pressure step test, in which the PCM commands and then measures a specific preprogrammed pressure and then measures time for pressure decay during the engine running test. If the PCM detects an EBP, EOT or IAT sensor fault it will disable the exhaust back pressure regulator.
Possible Solutions
Check the Exhaust Back Pressure Valve (EBPV) butterfly valve is opening and closing freely and not sticking. If it seems to move freely you can then check the connector and circuit for the EBPV solenoid.
The OBD2 Code Information Be Applicable For Seat:
2013 Seat Mii,2013 Seat Leon,2013 Seat Ibiza Cupra,2013 Seat Ibiza,2012 Seat Toledo Concept,2012 Seat Exeo ST,2012 Seat Exeo,2012 Seat Alhambra 4WD,2011 Seat Ibiza,2010 Seat Ibiza,2009 Seat Leon,2009 Seat Ibiza,2009 Seat Altea,2007 Seat Altea,2006 Seat Leon,2006 Seat Ibiza,2005 Seat Toledo,2005 Seat Altea,2004 Seat Ibiza,2004 Seat Cordoba,2002 Seat Ibiza
Note:
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