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Home >> Subaru >> 2012 >> Outback Base, Standard Trans >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4SO) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0442 Evaporative Emission Control System Leak Detected (Small Leak) >> Outline Of Diagnosis >> 4-inch Diagnosis

4-inch Diagnosis

Fig 1: 0.04-Inch Diagnosis Mode Description Chart
G04998198Courtesy of SUBARU OF AMERICA, INC.
Mode Mode Description Diagnosis Period
Mode Z
(Purge control solenoid valve opening failure diagnosis)
Perform purge control solenoid valve opening failure diagnosis from the size of tank pressure variation from diagnosis start. 5000 ms + 3000 ms - 5000 ms + 3000 ms + 13000 ms
Mode A
(Estimated evaporation amount)
Calculate the tank pressure change amount (P1). 10000 ms
Mode B
(Sealed negative pressure, large leakage judgment)
Decrease the pressure in the tank to the target value by introducing the intake manifold pressure to the fuel tank.
If the tank pressure cannot be reduced, it is diagnosed as large leak.
0 - 10000 ms + 25000 ms
Mode C
(Pressure increase check, advanced OK judgment)
Wait until the tank pressure returns to the target (start level of P2 calculation). If the tank pressure does not become the value, make advanced OK judgment. 0 - 14013 ms
Mode D
(Negative pressure variation measurement, evaporation leakage diagnosis)
Calculate the tank pressure variation (P2), and obtain the diagnostic value using P1 found in Mode A.
Perform the evaporation diagnosis using the diagnostic value.
0 ms + 10000 ms
MODE TABLE FOR EVAPORATIVE EMISSION CONTROL SYSTEM DIAGNOSIS

Mode Behavior of tank internal pressure under normal conditions Diagnostic item DTC
Mode Z Roughly the same as barometric pressure (Same as 0 kPa (0 mmHg, 0 inHg)) Purge control solenoid valve is judged to be open. P0457
Mode A Pressure is in proportion to amount of evaporative emission. - None
Mode B Negative pressure is formed due to intake manifold negative pressure Large leak P0457
Mode C Reaches target pressure - None
Mode D Pressure change is small. EVAP system large leak determination. [1.0 mm (0.04 in)] P0442