I have gotten the code P0455 twice now in 3 months. <a href="http://motorhaven.autoanything.com/">gas cap</a> is on good and tight from what I can tell. I have removed spare and looked over charcoal canister, looks ok. There is a valve on it that attaches to a hose that goes to a rectangular box attached to the upper body, there is nothing else attached to this box. The charcoal can. has an elect. harness connected to the valve and two other hose connections. All seem tight. The valve closes whan 12v is applied.

Up front I traced all hoses to another valve (Vapor Management Valve?) all look tight. There is a service port with a schrader valve and tag. Tag says Evap service port 1psi regulated only. Can someone assist me with some more ideas. I would also like to know what the service port is for and if another hose should attach to the rectangular box described above. Thanks,

Scott
sckent@tri-lakes.net

 

The P0455 means you have a big leak in the system somewhere....or it thinks you do.
All the pinpoint tests for it want a scan tool hooked up and a smoke machine for checking for a leak. The smoke machine gets hooked up to the test port you found and basically fills the whole system with smoke and you watch where it comes out.

The manual says this about how the system works.........

The evaporative emission system:

prevents hydrocarbon emissions from reaching the atmosphere.
stores fuel vapors in the evaporative emission (EVAP) canister (9D653).
returns the stored fuel vapors to the engine during engine operation.
has a remote evaporative emission test port located next to the fan shroud.
Fuel vapors are routed:

from the fuel tank (9002) through the two fuel vapor vent valves (9B593) to the evaporative emission canister through a vapor line.
from there, to the engine when the evaporative emission canister purge valve (9C915) is opened by the powertrain control module (PCM) (12A650).


The fuel tank pressure sensor (9C052):

monitors the fuel tank pressure.
provides a fuel tank pressure reading to the powertrain control module during the OBD II leak test.


The fuel tank filler cap:

relieves system pressure above 14 kPa (2 psi).
relieves system vacuum below 3.8 kPa (0.53 psi).


The evaporative emission canister purge valve (9C915):

regulates the purging of the evaporative emission canister.
is controlled by the powertrain control module.


The canister vent solenoid (9F945):

seals the evaporative emission system for the OBD II leak check.
is serviced as a separate item.


The evaporative emission canister:

is located behind the rear axle assembly.
contains activated carbon.
stores fuel vapors.


The evaporative emission dust separator (9B328):

is located above the cross frame rail, rear of center, before the evaporative emission canister.
prevents suspended dust and dirt particles from entering the evaporative emission system.
is serviced as a separate item.