Subaru 2009 IMPREZA Service Manual page 835

Diagnostic Trouble Code (DTC) Detecting Criteria
Mode D: (Measure amount of negative pressure change)
Monitor the tank pressure change amount when using mode D. In this case, the tank pressure increases,
(nears barometric pressure) because evaporation occurs. However, if any leakage exists, the pressure in-
creases additionally in proportion to this leakage. The pressure variation of this tank is P2.
After calculating P2, perform a small leak diagnosis according to the items below.
When Mode D is ended
Assign tank variations measured in Mode A and Mode D, P1 and P2, to the formula below, judge small leaks
in the system. If the measured judgement value exceeds the threshold value, it is judged to be a malfunction.
Abnormality Judgement
Judge as NG when the following conditions are established within the predetermined time. Judge as OK and
clear the NG if the following conditions are not established within the predetermined time.
Judgement Value
Malfunction Criteria
P2 – 1.5 – × P1
P2: Tank pressure that changes every
10000 ms in mode D
P1: Tank pressure that changes every
10000 ms in mode A
*1.5 –: Evaporation amount compensation value when below negative pressure (Amount of evaporation occurrence increases as
a vacuum condition increases.)
Map 5 Malfunction criteria limit for evaporation diagnosis
Fuel temperature vs. Fuel level
0 2 (0 US gal, 0 Imp gal)
10 2 (2.64 US gal, 2.2 Imp gal)
20 2 (5.28 US gal, 4.4 Imp gal)
30 2 (7.93 US gal, 6.6 Imp gal)
40 2 (10.57 US gal, 8.8 Imp gal)
50 2 (13.21 US gal, 11 Imp gal)
60 2 (15.85 US gal, 13.2 Imp gal)
Time Needed for Diagnosis: 0 ms + 3000 ms + 10000 ms + 10000 ms + 25000 ms + 18600 ms + 10000 ms
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-
cles.
Threshold Value
> Value of Map 5
25 °C (77 °F) 30 °C (86 °F)
0.3 kPa 0.3 kPa
(2.1 mmHg, (2.2 mmHg,
0.1 inHg) 0.1 inHg)
0.3 kPa 0.3 kPa
(2.1 mmHg, (2.2 mmHg,
0.1 inHg) 0.1 inHg)
0.3 kPa 0.3 kPa
(2.3 mmHg, (2.4 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.4 kPa
(2.9 mmHg, (3.05 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.4 kPa
(2.9 mmHg, (3.15 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.4 kPa
(3.2 mmHg, (3.3 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.4 kPa
(3.2 mmHg, (3.3 mmHg,
0.1 inHg) 0.1 inHg)
GD(H4SO)-111
DTC
P0442
35 °C (95 °F) 40 °C (104 °F) 45 °C (113 °F)
0.3 kPa 0.3 kPa
(2.3 mmHg, (2.35 mmHg,
0.1 inHg) 0.1 inHg)
0.3 kPa 0.3 kPa
(2.3 mmHg, (2.35 mmHg,
0.1 inHg) 0.1 inHg)
0.3 kPa 0.3 kPa
(2.5 mmHg, (2.6 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.4 kPa
(3.15 mmHg, (3.25 mmHg,
0.1 inHg) 0.1 inHg)
0.4 kPa 0.5 kPa
(3.3 mmHg, (3.4 mmHg,
0.1 inHg) 0.1 inHg)
0.5 kPa 0.5 kPa
(3.5 mmHg, (3.6 mmHg,
0.1 inHg) 0.1 inHg)
0.5 kPa 0.5 kPa
(3.5 mmHg, (3.6 mmHg,
0.1 inHg) 0.1 inHg)
GENERAL DESCRIPTION
0.3 kPa
(2.4 mmHg,
0.1 inHg)
0.3 kPa
(2.4 mmHg,
0.1 inHg)
0.4 kPa
(2.7 mmHg,
0.1 inHg)
0.4 kPa
(3.35 mmHg,
0.1 inHg)
0.5 kPa
(3.5 mmHg,
0.1 inHg)
0.5 kPa
(3.7 mmHg,
0.1 inHg)
0.5 kPa
(3.7 mmHg,
0.1 inHg)