Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p014c a/f / o2 sensor slow response - rich to lean bank 1 sensor 1

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h6do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p014c a/f / o2 sensor slow response - rich to lean bank 1 sensor 1

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Clear Memory Mode > OPERATION, and Inspection Mode Inspection Mode > PROCEDURE.

STEP	CHECK	YES	NO
1.CHECK EXHAUST SYSTEM. NOTE: Check the following items. • Loose installation of front portion of exhaust pipe onto cylinder heads • Loose connection between front exhaust pipe and front catalytic converter • Damage of exhaust pipe resulting in a hole	Is there any fault in exhaust system-	Repair the exhaust system.	Replace the front oxygen (A/F) sensor. Front Oxygen (A/F) Sensor

1. OUTLINE OF DIAGNOSIS

Detect the slow response of front oxygen (A/F) sensor.

For diagnosis, detect the trouble by processing the λ waveform in normal driving without forcibly changing the target air fuel ratio.

2. COMPONENT DESCRIPTION

(A)	Electromotive force	(B)	Air fuel ratio	(C)	Rich
(D)	Lean

(1)	Exhaust gas	(2)	ZrO2

3. EXECUTION CONDITION

Secondary Parameters	Execution condition
Battery voltage	> 10.9 V
Closed loop control of 3000 ms or more with main feedback	Operation
Engine speed	≥ 1000 rpm
Intake air amount	≥ 10 g/s (0.35 oz/s)

4. GENERAL DRIVING CYCLE

Perform diagnosis only once in a city driving including normal acceleration and deceleration.

5. 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”.

(A)

Time during which diagnosis is in progress

(B)

Cumulative value of time when λ changes from lean > rich

Judge as NG when the following conditions are established.

Judgment Value

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 P014E
	> 0.61	P014D and P014F

Time Needed for Diagnosis: 90000 ms

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

6. DIAGNOSTIC METHOD 2

Detect the malfunction by the cumulative value obtained from the amount of variation in λ change.

Judge as NG when the following conditions are established.

Judgment Value

Malfunction Criteria

Threshold Value

DTC

Cumulative value obtained from the amount of variation in λ change

Σ |(lambda(n) − lambda(n-1)) − (lambda(n-1) − lambda(n-2))|

< Value from Map

A pair of P014C/P014D and a pair of P014E/P014F are diagnosed respectively.

Map

Cumulative value obtained from the amount of variation in λ

Σ |lambda(n) − lambda(n-1)|

0.00

2.00

Cumulative value obtained from the amount of variation in λ change

0.00

2.00

Time Needed for Diagnosis: 90000 ms

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

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