Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc p0068 map/maf - throttle position correlation

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h4do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc p0068 map/maf - throttle position correlation

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 AIR INTAKE SYSTEM.	Are there holes, loose bolts or disconnection of hose on air intake system-	Repair the air intake system.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0068 MAP/MAF - THROTTLE POSITION CORRELATION
2.CHECK MANIFOLD ABSOLUTE PRESSURE SENSOR. 1) Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F). 2) For CVT models, set the select lever to “P” range or “N” range, and for MT models, place the shift lever in the neutral position. 3) Turn the A/C switch to OFF. 4) Turn all the accessory switches to OFF. 5) Read the value of «Mani. Absolute Pressure» using the Subaru Select Monitor or a general scan tool. NOTE: • Subaru Select Monitor For detailed operation procedures, refer to “Read Current Data For Engine”. Subaru Select Monitor • General scan tool For detailed operation procedures, refer to the general scan tool operation manual.	Is the value in «Mani. Absolute Pressure» 73.3 — 106.6 kPa (550 — 800 mmHg, 21.65 — 31.50 inHg) when the ignition is turned ON, and 20.0 — 46.7 kPa (150 — 350 mmHg, 5.91 — 13.78 inHg) during idling-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0068 MAP/MAF - THROTTLE POSITION CORRELATION	Replace the manifold absolute pressure sensor. Manifold Absolute Pressure Sensor
3.CHECK THROTTLE OPENING ANGLE. Using the Subaru Select Monitor or a general scan tool, read the value in «Throttle Opening Angle». NOTE: • Subaru Select Monitor For detailed operation procedures, refer to “Read Current Data For Engine”. Subaru Select Monitor • General scan tool For detailed operation procedures, refer to the general scan tool operation manual.	Is the value in «Throttle Opening Angle» with the throttle fully closed less than 5%-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0068 MAP/MAF - THROTTLE POSITION CORRELATION	Replace the electronic throttle control. Throttle Body
4.CHECK THROTTLE OPENING ANGLE.	Is the value in «Throttle Opening Angle» with the throttle fully open 85% or more-	Replace the manifold absolute pressure sensor. Manifold Absolute Pressure Sensor	Replace the electronic throttle control. Throttle Body

1. OUTLINE OF DIAGNOSIS

Detect problems in the intake manifold pressure sensor output properties.

Judge as NG when the intake air pressure AD value is Low whereas it seemed to be High from the viewpoint of engine condition, or when it is High whereas it seemed to be Low from the engine condition.

2. COMPONENT DESCRIPTION

(A)	Output voltage	(B)	Absolute pressure

(1)	Connector	(2)	Terminals	(3)	O-ring

3. EXECUTION CONDITION

Secondary Parameters	Execution condition
Low
Engine coolant temperature	≥ 60 °C (140 °F)
Engine speed	< 2500 rpm
Throttle position	≥ 12 ° (CVT model) ≥ 10 ° (MT model)
Engine load	> 0.6 g/rev (0.02 oz/rev) (CVT model) > 0.5 g/rev (0.02 oz/rev) (MT model)
High
Engine coolant temperature	≥ 60 °C (140 °F)
Engine speed	525 rpm — 875 rpm (CVT model) 550 rpm — 850 rpm (MT model)
Throttle position	< 5.7 °
Engine load	< 0.44 g/rev (0.02 oz/rev)

4. GENERAL DRIVING CYCLE

Perform the diagnosis continuously after idling.

5. DIAGNOSTIC METHOD

Judge as NG when Low side or High side becomes NG.

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
Low
Output voltage	< 1.46 V (CVT model) < 1.17 V (MT model)
High
Output voltage	≥ 3.5 V

Time Needed for Diagnosis:

Low side: 5000 ms

High side: 5000 ms

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

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