Diagnostic Method

Detect the trouble by calculating the time from the completion of the fuel cut to the beginning of the rear oxygen sensor voltage starting to rise.

Fig 1: Time From Completion Of Fuel Cut To Beginning Of Oxygen Sensor Voltage Rise

Courtesy of SUBARU OF AMERICA, INC.

Judge as NG when the following conditions are established.

JUDGMENT VALUE SPECIFICATION

Malfunction Criteria

Threshold Value

Output voltage value of rear oxygen sensor

< 0.2 V

Elapsed time⁽¹⁾

> Value from Map

⁽¹⁾	Elapsed time: The time since the λ became less than 1 after the end of fuel cut

Map

Except for PZEV model (CVT)

Amount of intake air g/s (oz/s)	10 (0.35)	12 (0.42)	14 (0.49)	16 (0.56)	18 (0.63)	20 (0.71)	40 (1.41)
Elapsed time (sec)	5500	4500	4000	3750	3500	3250	3000

Except for PZEV model (MT)

Amount of intake air g/s (oz/s)	10 (0.35)	12 (0.42)	14 (0.49)	18 (0.63)
Elapsed time (sec)	7000	6000	5500	5500

PZEV model

Amount of intake air g/s (oz/s)	13 (0.46)	14 (0.49)	16 (0.56)	18 (0.63)	20 (0.71)
Elapsed time (sec)	4900	4600	4300	4000	4000

Time needed for diagnosis: Less than 1 second

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