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Home >> Subaru >> 2009 >> Forester XT >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Diagnostic Trouble Code (DTC) Detecting Criteria (H4DOTC) >> Diagnostic Trouble Code (DTC) Detecting Criteria >> DTC P0171 System Too Lean (Bank 1) >> Diagnostic Method

Diagnostic Method

Compare the diagnosed value (fsobd) with the threshold value, and if a condition meeting the malfunction criteria below continues for 10 s x 5 time(s) or more, judge that there is a fault in the fuel system.

Judgement Value 

JUDGEMENT VALUE REFERENCE

Malfunction Criteria Threshold Value
fsobd = (sglmd - tglmda) + faf + flaf ≥ Value of Map 2
In this case: sglmd = measured lambda  
tglmda = target lambda  
faf = main feedback compensation coefficient every 64 milliseconds  
flaf = main feedback learning compensation coefficient  

MAP 2 

MAP SPECIFICATION

Amount of air (g (oz)/s) 0 (0) 2.34375 (0.08) 4.6875 (0.17) 7.03125 (0.25) 9.375 (0.33) 11.71875 (0.41) 14.0625 (0.5)
fsobdL 1 (%) 1.4 1.4 1.368623 1.319185 1.26975 1.265 1.265

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

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

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 

JUDGEMENT VALUE REFERENCE

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

Time Needed for Diagnosis:  10 s