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Home >> Subaru >> 2023 >> Ascent Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (2 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0172: System Too Rich Bank 1 >> General Description >> Diagnostic Method

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 Less than value of Map
{[Short term fuel trim B1] + [Long term fuel trim B1] + ([A/F Sensor #1] - [Target Equivalence Ratio]) x 100}  
WARM-UP INCREASE COMPENSATION COEFFICIENT - MAP

Warm-up increase compensation coefficient 0 0.05 0.1 0.14 0.2 0.25 0.3 0.35
Threshold Value 0.65 0.596 0.552 0.514 0.474 0.44 0.407 0.378

Time needed for diagnosis:  10 s x 3 times

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

NOTE: When a short period (distance) driving from the engine start to stop is repeated, engine warm-up followed may cause detection of P0172 due to gasoline evaporation within the engine oil and blow-by gas increase.