Diagnostic Method

Courtesy of SUBARU OF AMERICA, INC.

Mode	Explanation of Mode	DTC	Diagnosis period
A	Vacuum pump operation confirmation and characteristics stability	P2404	7 s or less
B	Measurement of reference pressure for setting the target negative pressure	P2404	350 s or less
C	Switching valve operation confirmation	P2404	12 s or less
D	Clogging of pipe diagnosis and leak pressure measurement	P1451	1100 s or less
D2	Check valve open stuck	P04AE	30 s or less
E	0.04 inch leak pressure measurement	P0455	50 s or less
	0.02 inch leak pressure measurement	P0456
	Reference pressure measurement for judgment	P2401

Courtesy 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.

Malfunction Criteria	Threshold Value	DTC
Pressure sensor output value	More than -0.22 kPa (-1.7 mmHg, -0.1 inHg)	P2404

<Mode B (measurement of reference pressure for setting the target negative pressure)> 

Judgment 1

Purpose: Judge the reference pressure stability.

Judge as NG when the following conditions are established.

Judgment 2, 3

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.

Malfunction Criteria	Threshold Value	DTC
<Judgment 1> |Pressure sensor maximum output value - Pressure sensor minimum output value| Or,	More than 0.49 kPa (3.7 mmHg, 0.1 inHg)	P2404
<Judgment 2> Reference pressure for setting the target negative pressure Or,	Less than value of Map2	P2404
<Judgment 3> Reference pressure for judgment	More than value of Map3	P2404

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))	-3.97 (-30, -1.2)	-4.08 (-31, -1.2)	-4.19 (-31, -1.2)	-4.29 (-32, -1.3)

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))	-0.94 (-7.1, -0.3)	-1.05 (-7.9, -0.3)	-1.16 (-8.7, -0.3)	-1.26 (-9.5, -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.

Malfunction Criteria	Threshold Value	DTC
Pressure sensor output value -Reference pressure for setting the target negative pressure	Less than 0.22 kPa (1.7 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.

Malfunction Criteria	Threshold Value	DTC
<Phase D> Time required to reach to the target negative pressure	40.9 seconds or less	P1451
<Phase D2> Reference pressure for judgment of the target negative pressure	More than -0.18 kPa (-1.4 mmHg, -0.05 inHg)	P04AE
<Large leak (0.04 inch)> Leak pressure	Value of Map4 or more	P0455
<Very small leak (0.02 inch)> Leak pressure	More than 0.018 inch reference pressure and Less than value of Map4	P0456

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

<Mode E (Measurement of reference pressure for judgment)> 

Judgment 1

Purpose: Judge the reference pressure stability.

Judge as NG when the following conditions are established.

Judgment 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 3

Purpose: Judge the presence of evaporative emission system leak.

Judge as NG when the following conditions are established.

Malfunction Criteria	Threshold Value	DTC
<Judgment 1> |Pressure sensor maximum output value - Pressure sensor minimum output value| Or,	More than 0.49 kPa (3.7 mmHg, 0.1 inHg)	P2404
<Judgment 2> Reference pressure for judgment Or,	Less than value of Map5 Or, More than value of Map6	P2404
<Judgment 3> |Reference pressure for setting the target negative pressure - Reference pressure for judgment|	More than 0.94 kPa (7.1 mmHg, 0.3 inHg)	P2404

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))	-4.54 (-34.1, -1.3)	-4.64 (-34.8, -1.4)	-4.75 (-35.6, -1.4)	-4.86 (-36.5, -1.4)

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))	-0.82 (-6.15, -0.2)	-0.93 (-6.98, -0.3)	-1.04 (-7.8, -0.3)	-1.14 (-8.55, -0.3)

Time needed for diagnosis:  27 min

Confirm the malfunction at next engine start.

Malfunction indicator light illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.