Well guys I been searching and looking around for solutions and answers but i got nothing. The P1440 indicates a small leak somewhere in the system and i just cant seem to find it.

I replaced the gas cap, inspected the vapor canister (no leaks) checked all the hoses (no leaks) I dont know what else to do, the damn code keeps coming back after about 45 miles or so.

The pressure is bleeding off somewhere but I just dont know where...


Any Input guys ?

 

Nobody has any input ?

 

Check your fuel filler neck. Check that there is no progressive rust. Also, since the fuel filler neck assembly also has a few vacuum lines, it could be possible that there are leaks in one or more of those lines. Blast your fuel filler neck with some brake cleaner and see if cleaning it some can reveal any breaches. Good luck.

 

I looked in the FSM and it gave some possible causes besides the gas cap. Here's a cut & paste:

If DTC P1440 is displayed with P1448, perform trouble diagnosis for DTC P1448 first.

* Incorrect fuel tank vacuum relief valve
* Incorrect fuel filler cap used
* Fuel filler cap remains open or fails to close.
* Foreign matter caught in fuel filler cap.
* Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve.
* Foreign matter caught in EVAP canister vent control valve.
* EVAP canister or fuel tank leaks
* EVAP purge line (pipe and rubber tube) leaks
* EVAP purge line rubber tube bent.
* Blocked or bent rubber tube to EVAP control system pressure sensor
* Loose or disconnected rubber tube
* EVAP canister vent control valve and the circuit
* EVAP canister purge volume control solenoid valve
* Absolute pressure sensor
* Fuel tank temperature sensor
* O-ring of EVAP canister vent control valve is missing or damaged.
* Water separator
* EVAP canister is saturated with water.
* Fuel level sensor and the circuit
* EVAP control system pressure sensor
* Refueling control valve
* ORVR system leaks

If you don't have the FSM, download it from here:

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

 

This worked for me, think I got lucky...

stop filling the tank when the automatic nozzle clicks off, - leaving the tank very full (like overnight) can have seepage into the evaporative tank. Then it may take 3-4 tanks for the tank to dry out.

click the gas cap 3 or 4 times, not just once.

I was getting repeated codes, replaced the gas cap, stopped overfilling, and making sure the cap is tight. Code has been gone a year now. Good luck on yours.

Chuck

 

What cap did you replace your with ? I inspected all the hoses and every single one of them is on tight with no leaks.

However im starting to think my EVAP canister vent control valve is busted as its rusted on the bottom. Pics will follow once i get this thing out...

 

So i finally got it out bouy was this thing rusted in. but with plenty of wd40 i got it out.
So what do you boys think would this valve cause a P1440 ? Its the only code im getting.

 

It is one of the possible causes of P1440. Can you determine if the plunger in the valve works? If it does, then it's not causing your problem.

 

I can put a flathead screwdriver in it and it just barely goes does a centimeter, I dont know how far its supposed to open and close.

Is there a way to test it with a multimeter or something ?

 

Sorry for the delay, I was travelling all week. I bought the cap from the dealer, I think it was about $20. BTW - I have an I-35, but the Nissan dealer was closer than an Infiniti dealer. The Nissan place had both and pulled them out. Different part #'s, Nissan was $20, Infiniti $30, and the caps looked identical.

I drive 150 miles a day, so I put gas in 2-3 times a week. It took about a week or so for my codes to clear, but they have not come back. I remember reading something about the canister getting saturated and needing time to dry out.

Also I think I had started only tightening the cap 1 click, now I tighten until there are 3-4 clicks. I also do not overfill past the auto shutoff.

Good luck.

 

The valve has been back in for a while,but it turns out my car doesn't like aftermarket gas caps (Stant) so after I fixed the rusty valve I still had the CEL.

Put the old oem cap back on and the CEL cleared itself out within a few days.
Aftermarket Gas caps dont seem to work guys !