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Home >> Subaru >> 2016 >> WRX STI Series.HyperBlue >> Repair and Diagnosis >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0455 EVAP System (CPC) Leak Detected (Large Leak) >> Diagnostic Method

Diagnostic Method

Fig 1: EVAP System Pressure Diagnosis Cycle Graph
G10291031Courtesy of SUBARU OF AMERICA, INC.
Mode Explanation of Mode Diagnosis Period
A Vacuum pump operation confirmation and characteristics stability 7 s or less & 300 s
B Measurement of reference pressure for setting the target negative pressure 40 s or less
C Switching valve operation confirmation 12 s or less
D Clogging of pipe diagnosis and leak pressure measurement 900 s or less
D2 Pipe clogging of the high pressure line Solenoid valve for secondary purge stuck closed 60s
E Reference pressure measurement for judgment 40 s or less
Fig 2: Evaporative Emission System Diagnosis Mode Chart
G10291032Courtesy of SUBARU OF AMERICA, INC.

Mode A (Vacuum pump operation confirmation and characteristics stability) 

Purpose: Detect the vacuum pump operation trouble.

Judge as NG when the following conditions are established.

Judge as OK if the following conditions are not established, and warm up for five minutes to stabilize the vacuum pump characteristics.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value DTC
Pressure sensor output value > -224 Pa (-1.68 mmHg, -0.1 inHg) P2404

Mode B (Measurement of reference pressure for setting the target negative pressure) 

  1. Purpose: Judge the reference pressure stability.

    Judge as NG when the following conditions are established.

    JUDGMENT VALUE SPECIFICATION

    Malfunction Criteria Threshold Value DTC
    |Pressure sensor maximum output value - Pressure sensor minimum output value| > 314 Pa (2.355 mmHg, 0.1 inHg) P2404
  2. Purpose: Judge whether the reference pressure is within the normal range, and detect the vacuum pump and orifice malfunctions.

    Judge as NG when the following conditions are established.

    JUDGMENT VALUE SPECIFICATION

    Malfunction Criteria Threshold Value DTC
    Reference pressure for setting the target negative pressure < Value of Map 2 P2404
      or  
      > Value of Map 3  
    BAROMETRIC PRESSURE SPECIFICATION - MAP 2

    Barometric pressure kPa (mmHg, inHg) 70 (525, 20.7) 80 (600, 23.6) 90 (675, 26.6) 100(750, 29.5)
    Reference pressure for setting the target negative pressure kPa (mmHg, inHg) -4 (-29.79, -1.2) -4.1 (-30.593, -1.2) -4.2 (-31.395, -1.2) -4.3 (-32.19, -1.3)
    BAROMETRIC PRESSURE SPECIFICATION - MAP 3

    Barometric pressure kPa (mmHg, inHg) 70 (525, 20.7) 80 (600, 23.6) 90 (675, 26.6) 100 (750, 29.5)
    Reference pressure for setting the target negative pressure kPa (mmHg, inHg) -0.9 (-7.065, -0.3) -1 (-7.86, -0.3) -1.2 (-8.663, -0.3) -1.3 (-9.465, -0.4)

Mode C (Switching valve operation confirmation) 

Purpose: Measure the pressure increase when switching valve is changed from open to close, and detect the stuck to open/close malfunctions of the switching valve.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value DTC
Pressure sensor output value - Reference pressure for setting the target negative pressure < 224 Pa (1.68 mmHg, 0.1 inHg) P2404

Mode D (Clogging of pipe diagnosis and leak pressure measurement) 

  1. Clogging of pipe 

    Purpose: Measure the time required for the evaporative emission system to reach the target negative pressure by the vacuum pump, and detect the clogging of pipe trouble.

    Judge as clogging of pipe malfunction if the evaporative emission system reaches to the target negative pressure within the specified time.

  2. Leak pressure measurement 

    Purpose: Measure the pressure (leak pressure) when the evaporative emission system becomes the negative pressure by the vacuum pump.

    Store the pressure as a leak pressure while the following conditions are met.

JUDGMENT VALUE SPECIFICATION

Conditions for storing the leak pressure Threshold Value
When any one of the followings is established:  
  • Reference pressure for setting the target negative pressure - Pressure sensor output value
 ≥ Value of Map 4
  • Pressure sensor output value
 < -5 kPa (-37.298 mmHg, -1.5 inHg)
  • Time of negative pressure introduction
 ≥ 900000 ms

Phase D2

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value DTC
Phase D ≤ 27000 ms P1451
or    
Phase D2 < -0.7 kPa (-5 mmHg, -0.2 inHg)  

Time Needed for Diagnosis:  24 min

Mode E (Measurement of reference pressure for judgment) 

  1. Purpose: Judge the reference pressure stability.

    Judge as NG when the following conditions are established.

    JUDGMENT VALUE SPECIFICATION

    Malfunction Criteria Threshold Value DTC
    |Pressure sensor maximum output value - Pressure sensor minimum output value| > 314 Pa (2.355 mmHg, 0.1 inHg) P2404
  2. Purpose: Judge whether the reference pressure is within the normal range, and detect the vacuum pump and orifice malfunctions.

    Judge the vacuum pump performance stability. Judge as NG when the following conditions are established.

    JUDGMENT VALUE SPECIFICATION

    Malfunction Criteria Threshold Value DTC
    Reference pressure for judgment < Value of Map 4 P2404
      or  
      >Value of Map 5  
    BAROMETRIC PRESSURE SPECIFICATION - MAP 4

    Barometric pressure kPa (mmHg, inHg) 70 (525, 20.7) 80 (600, 23.6) 90 (675, 26.6) 100 (750, 29.5)
    Reference pressure for judgment kPa (mmHg, inHg) -4.5 (-34.02, -1.3) -4.6 (-34.815, -1.4) -4.7 (-35.618, -1.4) -4.9 (-36.42, -1.4)
    BAROMETRIC PRESSURE SPECIFICATION - MAP 5

    Barometric pressure kPa (mmHg, inHg) 70 (525, 20.7) 80 (600, 23.6) 90 (675, 26.6) 100 (750, 29.5)
    Reference pressure for judgment kPa (mmHg, inHg) -0.8 (-6.18, -0.2) -0.9 (-6.983, -0.3) -1 (-7.785, -0.3) -1.1 (-8.58, -0.3)
  3. Purpose: Judge the presence of evaporative emission system leak.

    Judge as NG when the following conditions are established.

    JUDGMENT VALUE SPECIFICATION

    Malfunction Criteria Threshold Value DTC
    < Large leak (0.04 inch) >   P0455
    Leak pressure ≥ Map6 (Pa)  
    lleakjdg = (Reference pressure for judgment) X 0.377 - (-45.5 Pa)    
    < Very small leak (0.02 inch) >   P0456
    Leak pressure < Map6 (Pa)  
    VALUE SPECIFICATION - MAP 6

    Reference pressure (Pa) -4856 -4000 -2750 -1500 -824
    Threshold Value (Pa) -1785 -1463 -991 -520 -265

Formula for threshold value = Reference pressure X 0.377 - -0.341 mmHg

Time Needed for Diagnosis:  Approx. 24 min

At next engine start, confirm whether the enable conditions are satisfied even though refueling has been done during soaking, and determine the malfunction.

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

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