Subaru 2009 IMPREZA Service Manual page 1629

Diagnostic Trouble Code (DTC) Detecting Criteria
5. DIAGNOSTIC METHOD
• Abnormality Judgement
Judge as NG if the criteria below are met.
Judgement Value
Malfunction Criteria
Engine coolant temperature
Timer for diagnosis after engine start
Timer for diagnosis after engine start
a. Timer stop at fuel cut
b. During the driving conditions except a) above, timer counts up as follows.
64 milliseconds + TWCNT milliseconds (the time of at 64 milliseconds)
TWCNT is defined as follows,
TWCNT = 0 at idle switch ON,
TWCNT show on the following table at idle switch OFF.
–20 (–4)
–10 (14)
Temperature
0 (32)
°C (°F)
10 (50)
20 (68)
Judgement value of timer after engine starting
t = 451056 ms – 25870 ms × Ti
Ti : The lowest coolant temperature after engine start
Time Needed for Diagnosis: Less than 1 second
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cy-
cles.
• Normality Judgement
Judge as OK and clear the NG when the malfunction criteria below are met.
Judgement Value
Malfunction Criteria
Engine coolant temperature
Time Needed for Diagnosis: Less than 1 second
Threshold Value
< 20 °C (68 °F)
Judgement value of
timer after engine start
0 (0) 8 (5) 16 (9.9)
0 ms 37.136 ms 74.272 ms
0 ms 27.391 ms 54.782 ms
0 ms 17.646 ms 35.292 ms
0 ms 7.9012 ms 15.802 ms
0 ms 7.9012 ms 15.802 ms
Threshold Value
20 °C (68 °F)
GD(H4DOTC)-41
Vehicle speed km/h (MPH)
24 (14.9) 32 (19.9)
111.41 ms 126.66 ms 141.91 ms
82.173 ms 99.65 ms 117.13 ms
52.938 ms 72.64 ms 92.341 ms
23.704 ms 45.63 ms 67.556 ms
23.704 ms 45.63 ms 67.556 ms
GENERAL DESCRIPTION
40 (24.9) 48 (29.8) 56 (34.8)
163.59 ms 185.26 ms
135.96 ms 154.8 ms
108.34 ms 124.33 ms
80.711 ms 93.867 ms
80.711 ms 93.867 ms