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">Go to Step 2.
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 gear 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 “Current Data Display 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">Go to Step 3.
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 “Current Data Display 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">Go to Step 4.
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 speed | < 4000 rpm |
Engine load | > 0.71 g/rev (0.03 oz/rev) (CVT model) > 0.71 g/rev (0.03 oz/rev) (MT model) |
Throttle position | ≥ 14 ° (CVT model) ≥ 14 ° (MT model) |
High | |
Engine speed | 500 rpm — 800 rpm (CVT model) 500 rpm — 950 rpm (MT model) |
Engine load | < 0.31 g/rev (0.01 oz/rev) |
Throttle position | ≤ 5 ° |
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.
Malfunction Criteria | Threshold Value |
Low | |
Output voltage (Manifold absolute pressure) Less than 57.73 kPa (433.1 mmHg, 17.05 inHg) | < 2.332 V (CVT model) < 2.332 V (MT model) |
High | |
Output voltage (Manifold absolute pressure) Less than 57.73 kPa (433.1 mmHg, 17.05 inHg) | ≥ 2.332 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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Always ensure that the rear gate is properly locked before leaving the vehicle
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