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Home >> Subaru >> 2021 >> Forester Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) >> Diagnostic Procedure With Diagnostic Trouble Code (DTC) >> DTC P0401: EGR Abnormal (EGR Amount Too Small) >> General Description >> Diagnostic Method

Diagnostic Method

The assumed intake manifold pressure (reference pressure) is calculated from engine speed, throttle opening angle and atmospheric pressure when the execution condition is established.

  1. When the execution condition is satisfied and the EGR valve sends the opening command (57 step), EGR under flow rate (P0401) is detected when the difference between the measured intake manifold pressure and the reference pressure (for 57 step) is equal to or more than the judgment value.
  2. When the execution condition is satisfied and the EGR valve sends the closing command (0 step), EGR over flow rate (P0402) is detected when the difference between the measured intake manifold pressure and the reference pressure (for 0 step) is equal to or more than the judgment value.
  3. Both P0401 and P0402 are detected if both judgment values are exceeded.

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value DTC
<Low flow rate monitor> Intake manifold absolute pressure for reference - Average value of intake manifold absolute pressure More than value of Map3 P0401
<High flow rate monitor> Average value of intake manifold absolute pressure - Intake manifold absolute pressure for reference More than value of Map4 P0402
MAP SPECIFICATION 3

  Engine speed (rpm)
1000r pm 1200r pm 1400r pm 1600r pm 1800r pm 2000r pm 2200r pm 2400r pm
Barometric pressure (kPa (mmHg, inHg)) 75.1 (563, 22.2 i nHg) 25.3 (190, 7.5 in Hg) 24 (180, 7.1 in Hg) 22.7 (170, 6.7 in Hg) 20.7 (155, 6.1 in Hg) 19.3 (145, 5.7 in Hg) 18 (135, 5.3 in Hg) 16.7 (125, 4.9 in Hg) 15.3 (115, 4.5 in Hg)
86.7 (650, 25.6 i nHg) 29.3 (220, 8.7 in Hg) 28 (210, 8.3 in Hg) 26 (195, 7.7 in Hg) 24.7 (185, 7.3 in Hg) 22.7 (170, 6.7 in Hg) 20.7 (155, 6.1 in Hg) 19.3 (145, 5.7 in Hg) 18.7 (140, 5.5 in Hg)
101.3 (760, 29.9 i nHg) 34.7 (260, 10.2 i nHg) 33.3 (250, 9.8 in Hg) 32 (240, 9.4 in Hg) 28 (210, 8.3 in Hg) 27.3 (205, 8.1 in Hg) 25.3 (190, 7.5 in Hg) 24.7 (185, 7.3 in Hg) 23.3 (175, 6.9 in Hg)
(kPa (mmHg, inHg))
MAP SPECIFICATION 4

  Engine speed (rpm)
1000r pm 1200r pm 1400r pm 1600r pm 1800r pm 2000r pm 2200r pm 2400r pm
Barometric pressure (kPa (mmHg, inHg)) 75.1 (563, 22.2 i nHg) 13.3 (100, 3.9 in Hg) 12 (90, 3.5 in Hg) 11.3 (85, 3.3 in Hg) 10 (75, 3inHg) 8.7 (65, 2.6 in Hg) 7.3 (55, 2.2 in Hg) 6 (45, 1.8 in Hg) 4.7 (35, 1.4 in Hg)
86.7 (650, 25.6 i nHg) 14 (105, 4.1 in Hg) 12.7 (95, 3.7 in Hg) 12 (90, 3.5 in Hg) 10.7 (80, 3.1 in Hg) 9.3 (70, 2.8 in Hg) 8 (60, 2.4 in Hg) 6.7 (50, 2inHg) 5.3 (40, 1.6 in Hg)
101.3 (760, 29.9 i nHg) 16 (120, 4.7 in Hg) 14.7 (110, 4.3 in Hg) 13.3 (100, 3.9 in Hg) 11.3 (85, 3.3 in Hg) 10 (75, 3inHg) 8.7 (65, 2.6 in Hg) 7.3 (55, 2.2 in Hg) 6 (45, 1.8 in Hg)
(kPa (mmHg, inHg))

Time needed for diagnosis  : 3200 ms

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