Subaru Crosstrek Service Manual: Dtc p0451 evap system (cpc) pressure sensor/switch circuit range/performance
ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)
DTC P0451 EVAP SYSTEM (CPC) PRESSURE SENSOR/SWITCH CIRCUIT RANGE/PERFORMANCE
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 FOR ANY OTHER DTC ON DISPLAY.
Is any other DTC displayed?
Check the appropriate DTC using the “List of Diagnostic Trouble Code (DTC)”. List of Diagnostic Trouble Code (DTC)">
Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC P0451 EVAP SYSTEM (CPC) PRESSURE SENSOR/SWITCH CIRCUIT RANGE/PERFORMANCE">Go to Step 2.
2.CHECK CURRENT DATA.
1) Turn the ignition switch to ON (engine OFF).
2) Using the Subaru Select Monitor or general scan tool, read the value in «Absolute Evap Sys. Pressure» and «Mani. Absolute Pressure», and compare them with the actual atmospheric pressure.
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.
• To read the actual atmospheric pressure, connect the Subaru Select Monitor or general scan tool to the other known good vehicle.
Is the difference with the actual atmospheric pressure 2.4 kPa (18 mmHg, 0.7 inHg) or more?
Replace the part that showed larger deviation from the actual atmospheric pressure than the other.
• If deviations in value for «Absolute Evap Sys. Pressure» is larger: Replace the leak check valve assembly. Leak Check Valve Assembly">
• If deviations in value for «Mani. Absolute Pressure» is larger: Replace the manifold absolute pressure sensor. Manifold Absolute Pressure Sensor">
Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
NOTE:
In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
1. OUTLINE OF DIAGNOSIS
Detect the output characteristics malfunction of Evaporative Leak Check Module pressure sensor.
Judge as NG when the Evaporative Leak Check Module pressure sensor output value is largely different from the intake manifold pressure when the ignition switch is ON.
2. COMPONENT DESCRIPTION
(1) | Leak check valve ASSY | (5) | Vacuum pump | (9) | Fuel tank |
(2) | Switching valve | (6) | Drain filter | (10) | Canister |
(3) | Reference orifice (0.02 inch orifice) | (7) | Purge control solenoid valve | ||
(4) | Pressure sensor | (8) | Intake manifold |
3. EXECUTION CONDITION
Secondary parameters | Execution condition |
Elapsed time after ignition switch is turned to ON | ≥ 500 ms and < 60000 ms |
Soaking time | ≥ 60 s |
Evaporative Leak Check Module vacuum pump | Not in operation |
Evaporative Leak Check Module switching valve | Open |
Purge control | Not in operation |
4. GENERAL DRIVING CYCLE
Perform the diagnosis once at ignition ON.
5. DIAGNOSTIC METHOD
If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.
Malfunction Criteria | Threshold Value |
Absolute value | |
(Evaporative Leak Check Module pressure sensor output value − intake manifold pressure (absolute pressure) when ignition switch is ON) | > 4.7 kPa (35.5 mmHg, 1.4 inHg) |
Time needed for diagnosis: 320 ms
Malfunction indicator light illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.
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