Diagnostic Method 1

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 Graph (Diagnostic Method 1)

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

Judgment Value

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria	Threshold Value	DTC
(Cumulative value of time when λ changes from lean → rich)/(Time during which diagnosis is in progress)	< 0.38	P014C
	> 0.61	P014D

Time Needed for Diagnosis: 120 seconds

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