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Home >> Subaru >> 2023 >> Ascent Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0171: System Too Lean Bank 1 >> Diagnostic Method
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Diagnostic Method

Compare the diagnostic value with the threshold value, and if a condition meeting the criteria continues for 10 s x 3 times or more, judge that there is a fault in the fuel system.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value
Diagnostic value
{[Short term fuel trim B1] + [Long term fuel trim B1] + ([A/F Sensor #1] - [Target Equivalence Ratio]) x 100}		 More than 1.35

Time needed for diagnosis:  10 s x 3 times

Malfunction indicator light illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

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