CAR OBD CODES
OBD/DTC Search, e.g.P0477
CAR OBD CODES P0477
P0477 OBD Code Definition:
P0477 Exhaust Pressure Control Valve Low
P0477 OBD Code Description:
OBD2 Code P0477 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 P0477
– Engine Light ON (or Service Engine Soon Warning Light)
Possible Causes
Possible causes of P0477
– 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.
Note: The information on the P0477 error code is purely informative, if you need more useful information, please consult your technician.
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C0000 C1A05 C1478 C1102 C1500 C0236 C1499 C1954 C1991 C0010 C1878 C116A C2784 C1699 C1266 OBDII Network Codes
U0423 U1149 U1071 U0327 U2613 U1207 U1109 U0126 U0035 U260A U1A00 U0243 U0411 U1005 U1169 OBDII Powertrain Codes
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