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Home >> Subaru >> 2017 >> Crosstrek Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Diagnostics) (P000A To P015B) (H4DO) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P014:C A/F/O2 Sensor Slow Response - Rich To Lean Bank 1 Sensor 1 >> Diagnostic Method 1 >> Notes
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Diagnostic Method 1: Notes

Detect the malfunction by checking "Cumulative value of time when λ changes from lean → rich" in comparison to "Time during which diagnosis is in progress".

Fig 1: Front Oxygen (A/F) Sensor λ - Time Graph
G11590142Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

Diagnosis (CVT model) 

MALFUNCTION CRITERIA

Malfunction Criteria Threshold Value DTC
(Cumulative value of time when λ changes from lean → rich)/(Time during which diagnosis is in progress) < 0.39 P014C
and    
Average value of time necessary for λ to inverse the air fuel ratio to Lean → Rich → Lean < 30 ms  
(Cumulative value of time when λ changes from rich → lean)/(Time during which diagnosis is in progress) > 0.63 P014D
and    
Average value of time necessary for λ to inverse the air fuel ratio to Rich → Lean → Rich > 20 ms