DTC P0451 Evaporative Emission System Pressure Sensor/Switch Range/Performance: DTC Detecting Condition

Detected when 2 consecutive driving cycles with fault occur.
GENERAL DESCRIPTION. Refer to DTC P0451 EVAPORATIVE EMISSION SYSTEM PRESSURE SENSOR/SWITCH RANGE/PERFORMANCE .

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

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)". Refer 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 «Atmosphere 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". Refer 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 atmospheric pressure 27 kPa (200 mmHg, 7.9 inHg) or more?	Replace the parts that showed deviations from the actual atmospheric pressure. If deviations are found in value for «Atmosphere Pressure»: Replace the leak check valve assembly. Refer to LEAK CHECK VALVE ASSEMBLY . If deviations are found in value for «Mani. Absolute Pressure»: Replace the manifold pressure sensor. Refer to 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.