Nissan Repair: 02 nissan pathfinder trouble codes, charcoal canister, nissan pathfinder

Question
Dear Sir;I recently had the check engine light on my pathfinder come on,I checked the codes(po1448,p0455)and my mechanic changed the charcoal canister and sensor on it.The canister had a bolt missing where the sensor bolts on and a 2in. crack on top,The codes were cleared.After about 20 or so miles the same codes appeared,my mechanic now changed a part on top of intake plenum I believe was called a volume solinod.Once again the check engine light with a code p0455 and now a code p0447.I know the codes means I just don't know where to look next? Also I did replace the gas cap.Any ideas where to look next? Thanks George

Answer
George,

Both codes point to the solenoid control valve and the evaporative control system.  I would be looking at loose or cracked hoses from the gas tank to the charcoal canister as well as from the canister to the engine.  And, I would actuate the valve and see if it works.  Now, there is a timed relay that turns on this valve when the car is started to vent the vapor to the engine.  Any other time it is closed and only allows the fuel to return to the tank after it condences.  If you top your car off too full it will overfill the canister and do all sorts of strange things.  Now, if not the other items are where you need to have your mechanic look.  In 2003 there was a technical service bulletin on Nissan's for defective fuel lines and vapor lines.  But, unless yours is a really late manufactured 2002 it would not apply to you.  And the codes you are getting are not that the system is not staying pressurized but are specific to the vent system.