Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0172 system too rich bank 1

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h6do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0172 system too rich bank 1

NOTE:

Refer to DTC P0175 for diagnostic procedure. Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0175 SYSTEM TOO RICH BANK 2

1. OUTLINE OF DIAGNOSIS

Detect fuel system malfunction by the amount of main feedback control.

2. EXECUTION CONDITION

Secondary Parameters	Execution condition
A/F main feedback function	In operation

3. GENERAL DRIVING CYCLE

Perform the diagnosis continuously during the closed loop.

4. DIAGNOSTIC METHOD

Compare the diagnostic value (fsobd) with the threshold value, and if a condition meeting the malfunction criteria listed below continues for 10 s - 3 time(s) or more, judge that there is a fault in the fuel system.

Judgment Value

Malfunction Criteria	Threshold Value
fsobd = (sglmd − tglmda) + faf + flaf	< Value from Map
In this case: sglmd = measured lambda
tglmda = target lambda
faf = main feedback compensation coefficient (every 64 milliseconds)
flaf = main feedback learning compensation coefficient

Map

Warm-up increase compensation coefficient	0.000	0.102	0.199	0.301
Threshold Value	0.67 − 0.000	0.67 − 0.105	0.67 − 0.177	0.67 − 0.241

Warm-up increase compensation coefficient	0.398	0.450
Threshold Value	0.67 − 0.295	0.67 − 0.319

Time Needed for Diagnosis: 10 s - 3 time(s)

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

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