Subaru 2009 IMPREZA Service Manual page 863

Diagnostic Trouble Code (DTC) Detecting Criteria
BU:DTC P0506 IDLE AIR CONTROL SYSTEM RPM LOWER THAN EXPECTED
1. OUTLINE OF DIAGNOSIS
Detect the malfunction that actual engine speed is not close to target engine speed during idling. Judge as
NG when actual engine speed is not close to target engine speed during idling.
2. ENABLE CONDITION
Secondary Parameters
Engine coolant temperature
Battery voltage
Barometric pressure
Fuel level
Elapsed time after starting the engine
Feedback of ISC
Lambda value (left and right)
After switching air conditioner to ON/
OFF
After intake manifold pressure changes
by 4 kPa (30 mmHg, 1.2 inHg) or more.
Elapsed time after switching neutral
position switch to ON/OFF
Vehicle speed
3. GENERAL DRIVING CYCLE
Perform the diagnosis continuously at idling after warming up engine.
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
Actual engine speed — Targeted engine
speed
Feedback value for ISC
Time Needed for Diagnosis: 10 s × 3 time(s)
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
Actual engine speed — Targeted engine
speed
Time Needed for Diagnosis: 10 s
Enable Condition
75 °C (167 °F)
10.9 V
75 kPa (563 mmHg,
22.2 inHg)
9.6 2 (2.54 US gal,
2.11 Imp gal)
10.49 s
In operation
0.81
and
< 1.1
5.1 s
> 5.1 s
> 5.1 s
0 km/h (0 MPH)
Threshold Value
< –100 rpm
Max.
Threshold Value
–100 rpm
GD(H4SO)-139
GENERAL DESCRIPTION