Testing the system an not replacing parts is the way to find the problem . Without knowing how ,using a factory diagnostic flow chart to go by would be best for a rookie .
System Description
The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.
Conditions For Setting the DTC
The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.
Diagnostic Aids
• To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.
• A temporary blockage in the EVAP purge solenoid, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
• To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with theJ 41413-SPT .
• Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
• For intermittent conditions refer to Intermittent Conditions .
Inspect the EVAP system for the following conditions:
• A loose, missing, or damaged service port schrader valve
• A loose, incorrect, missing, or damaged fuel fill cap
• A damaged EVAP purge solenoid
Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
Inspect the EVAP system for the following conditions:
• Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses
• A damaged EVAP vent solenoid or EVAP canister
Did you find and correct the condition?
Smoke testing the evap system to find the leak would be your best bet .
SOURCE: codes P0440 and P0300
the evap can simply be the gaz cap the 300 check for a good spark you may need wire and plug be carefull for those coil they offent defect good luck pierre
SOURCE: 2008 suburban i have code
sad to say that you miss on what you did, dtc P0449 was related to vent solenoid contol circuit, purge problem indicates P0443,, check the vent valve connectors supply voltage from the power distribution box, (fuse # 14-tcm/batt) and the other wire(almost white) to ecm C1 #61.
SOURCE: getting an error code of PO449 for a check engine
You are right. You need the vent valve not the purge valve. The vent valve is a dealer item. Also this is a common problem and GM has released a bulletin on this that involves moving the location of the valve and running some new lines. It comes as a kit from GM, and it costs about a 100 bucks.
SOURCE: I got a Error Code
P1442 usually gas cap. P1449 usually vent solenoid. P1441 usually always a faulty FTP sensor. Very problematic to Malibu, Grand Am Cavaliers and Aleros. That would be my first area to check. They are also known for poor wiring connections at the Left rear passthru connector to the fuel tank and vent solenoid, but not necessarily for that code.
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