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Home >> Subaru >> 2019 >> WRX Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Diagnostics) (Except For STI) (1 Of 4) >> Diagnostic Procedure With Diagnostic Trouble Code (DTC) >> DTC P015A: A/F/O2 Sensor Delayed Response - Rich To Lean Bank 1 Sensor 1 >> Diagnostic Method 1

Diagnostic Method 1

Detect the malfunction depending on the average value of time necessary for λ to inverse the air fuel ratio from "Lean → Rich → Lean" to "Rich → Lean → Rich".

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Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria Threshold Value DTC
Average value of time necessary for λ to inverse the air fuel ratio to Lean → Rich → Lean and > 80 ms P015A
Average value when λ is lean > 100 ms  
Average value of time necessary for λ to inverse the air fuel ratio to Rich → Lean → Rich > 70 ms P015B
and
Average value when λ is rich
> 110 ms (CVT model)
> 140 ms (MT model)
 

Time needed for diagnosis:  100 times of inversion

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