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Home >> Subaru >> 2012 >> Forester X, Automatic Trans >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4DO) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0171 System Too Lean (Bank 1) >> Diagnostic Method
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Diagnostic Method

JUDGMENT VALUE REFERENCE CHART

Malfunction Criteria Threshold Value
fsobd = (sglmd - tglmda) + faf + flaf
In this case: sglmd = measured lambda
tglmda = target lambda
faf = Main feedback compensation coefficient (every 64 ms)
flaf = main feedback learning compensation coefficient
≥ Value from Map 2
ENGINE COOLANT TEMPERATURE REFERENCE CHART

Amount of air (g (oz)/s) 0(0) 3.2 (0.11) 6.4 (0.23) 9.6 (0.34) 12.8 (0.45) 16 (0.56) 19.2 (0.68)
fsobdl.1 (%) 1.4 1.4 1.332 1.25 1.25 1.25 1.25

Time Needed for Diagnosis:  10 s x 5 time(s)

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

JUDGMENT VALUE REFERENCE CHART

Malfunction Criteria Threshold Value
fsobd = (sglmd - tglmda) + faf + flaf < 1.2

Time Needed for Diagnosis:  10 s