Subaru 2009 IMPREZA Service Manual page 1813

Diagnostic Trouble Code (DTC) Detecting Criteria
EI: DTC P2431 SECONDARY AIR INJECTION SYSTEM AIR FLOW /PRESSURE
SENSOR CIRCUIT RANGE/PERFORMANCE
1. OUTLINE OF DIAGNOSIS
Detect the malfunction of secondary air pressure sensor output property.
Judge as NG when the secondary air pressure sensor output is largely different from the intake manifold
pressure at engine start.
2. ENABLE CONDITIONS
Secondary Parameters
Engine speed
Vehicle speed
After secondary air system stops
3. GENERAL DRIVING CYCLE
Perform the diagnosis with ignition switch ON.
4. DIAGNOSTIC METHOD
• Abnormality Judgement
If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.
Judgement Value
Malfunction Criteria
|Secondary air pipe pressure – Intake
manifold pressure|
|Intake manifold pressure at engine start
– Intake manifold pressure|
Time Needed for Diagnosis: 328 ms
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-
cles.
• Normality Judgement
Judge as OK and clear the NG if the continuous time while the following conditions are established is more
than the predetermined time.
Judgement Value
Malfunction Criteria
|Secondary air pipe pressure – Intake
manifold pressure|
Time Needed for Diagnosis: 262 ms
Enable Condition
< 300 rpm
< 1 km/h (0.6 MPH)
2976 ms
Threshold Value
26.7 kPa (200 mmHg,
7.9 inHg)
< 1.3 kPa (9.99 mmHg,
0.4 inHg)
Threshold Value
< 26.7 kPa (200 mmHg,
7.9 inHg)
GD(H4DOTC)-225
GENERAL DESCRIPTION