DTC P0451 EVAP System (CPC) Pressure Sensor/Switch Circuit Range/Performance: DTC Detecting Condition

Detected when two consecutive driving cycles with fault occur.
GENERAL DESCRIPTION < Ref. to DTC P0451 EVAP SYSTEM (CPC) PRESSURE SENSOR/SWITCH CIRCUIT RANGE/PERFORMANCE , Diagnostic Trouble Code (DTC) Detecting Criteria. >

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. >, and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

DIAGNOSTIC 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)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2 CHECK CURRENT DATA. Turn the ignition switch to ON (engine OFF). 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 "Read Current Data For Engine". < Ref. to 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 barometric pressure 6.2 kPa (46.5 mmHg, 1.8 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. < Ref. to LEAK CHECK VALVE ASSEMBLY . > If deviations in value for «Mani. Absolute Pressure » is larger: Replace the manifold absolute pressure and intake air temperature sensor. < Ref. to MANIFOLD ABSOLUTE PRESSURE AND INTAKE AIR TEMPERATURE 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.