So i got these 2 codes showing for a while now i need to run my car through inspection and a mechanic i went to told me $400 to fix it, I cant afford that now so my friend who's uncle is a mechanic said that he would help us but not do the labor. the codes are p0450 which is the evaporative emissions system control pressure sensor and p0446 which is the vent control valve. I been doing a lot of research and can't find anything at all. All i see is that a lot of people are having the same problem...I went to the nissan dealership and the guy didnt know wtf i was talking about..so i went did research and found out about the sensor i called and told them and now they want a part number..I need to fix this before june 11th before my court date. I also saw that by cleaning the valves and canister would help but im not sure what's what. and me and my friend will try to fix it we have experience on fixing cars and stuff but not emissions. Does any of you have a picture which wll show me what valve and solenoid is which or a clear diagram about it? anything that would help me I will appreciate cause this thing is really starting to get me frustrated. Thank in advanced

 

Start by downloading the FSM for your car from here:

http://boredmder.com/FSMs/Nissan/Maxima/



This drawing is from beneath the car, looking at the driver's side rear wheel.

For P0466 code, start following the proceedure in section EC, page 241. Sometimes this valve can be cleaned and lubricated.The EVAP Canister Vent Control Valve (P0446) is part number 14935-54U1A.

For the P0450 code, start following the proceedure in section EC, page 248. The EVAP Control System Pressure Sensor (P0450) is part number 25085-54U01.

I'm pretty sure that I have the correct part numbers, but if you are going to buy a part, get them verified by the parts guy. They are found in section D, Engine Electrical, sub-section 223, Vacuum Piping.

 

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Definitely start with the vent valve cleaning and reset the codes. If it reappears, you will have to replace the vent valve.

 

oh man thanks a lot guys i really appreciate it big time

 

If I had to guess, the P0450 is caused by the P0446 like others have said. Fix the vent control valve first, reset codes and see what happens. Thats the easiest fix 2 10 mm bolts and a hose and electrical connector to remove it. Try a JunkYard for a "new" one if you cant get yours to work by following the video provided above, but make sure the plunger moves if you get one from a JY.

Heres a couple links for you as well

Code P0450

Code P0446

Also, in your 1st post, you wrote P0466 which is an unfounded code...so you may want to change that to the correct one which is P0446 to limit any confusion

 

yeah you're right i didnt notice it but yeah i keep on being told to check with the valve first i will try to clean it first hopefully itll work since JY will be closed on sunday but thanks a lot guys

 

Word of advice, use PB Blast (stronger than WD40) and let it sit in there before you try moving the plunger with a screwdriver. I used too much force on mine and didnt let it sit long enough and ended up ripping the rubber seal around the plunger by using said too much force Lol