Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0721 output shaft speed sensor circuit range/performance

Subaru Legacy BN/BS (2015-2019) Service Manual / Continuously variable transmission (diagnostics) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0721 output shaft speed sensor circuit range/performance

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

• Acceleration is poor during standing start.

• No lock-up occurs.

• The engine stalls when the vehicle is stopped.

• Shift control malfunction

STEP	CHECK	YES	NO
1.CHECK DTC. Read the DTC using Subaru Select Monitor.	Besides DTC P0721, is DTC P0500 displayed-	Perform the diagnosis according to DTCs other than P0721.	Perform the diagnosis according to DTC P0720. Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0720 OUTPUT SHAFT SPEED SENSOR CIRCUIT

1. OUTLINE OF DIAGNOSIS

• Detect the malfunction of front wheel speed sensor characteristics.

• Judge as NG when the deviation between vehicle speed from VDC and front wheel speed sensor becomes equal to or larger than the predetermined value.

2. EXECUTION CONDITION

Secondary Parameters	Execution condition
12 V battery system voltage	≥ 10 V
Vehicle speed (from vehicle dynamics control module)	≥ 12 MPH

3. DIAGNOSTIC METHOD

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

Judgment Value

Malfunction Criteria	Threshold Value
\|Vehicle speed (calculated from front output shaft speed) − Vehicle speed (from vehicle dynamics control module)\|	> 10 MPH

Time Needed for Diagnosis: 5 seconds

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

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