I bought a 2003 neon sxt 4-cyl manual transmission car. It has the code for a small EVAP leak and the code for a medium evap leak. I changed the canister, leak detection pump, and the breather/filter that comes off of the leak detection pump as well as the hoses that connect all the parts. It is still displaying the codes for the evap leaks. I paid a shop to do a smoke test before I replaced all the parts, and they told me it was the canister and the vent valve. When I bought the parts from the dodge dealership they said there was no vent valve so I just changes all three EVAP system parts and still get the codes and bad gas mileage. I was now considering what the shop said about the vent valve so I looked up vent valves for neon sxt on the web and it showed results for the PCV valve. Is this what the shop was referring to as the "vent valve." If not, could anyone help me out by informing me of what to do to find this leak without paying a lot of money to the shop?

 

Check the lines that come off of the canister for cracks. Check your gas cap gasket as well.

 

I replaced all hoses that connect all EVAP system parts. All hoses under the hood and the car that I can see look great. I replaced the gas cap when I first bought the car. I have literally replaced the entire EVAP system, well at least all EVAP parts listed in the repair manual along with all hoses that looked bad. The only hose I did not check was the one that runs from the cnister to the front of the car, but from what I can see of it, the hose still looks good. The shop told me the canister and vent valve was the problem. I changed the canister, but the dealership showed no parts called "vent valve" so I was wondering why they would say the "vent valve" is bad if the dealership said there was no "vent valve" for my car. I searched "Dodge neon sxt vent valve" and got results for a PCV valve. I am just tired of messing with this thing. Also, would a bad gas cap cause the car to get poor gas mileage (Like 25 or less highway). I would figure tat with a 4 cylinder I would get at least 30 on the highway (doing the speed limit and not 100 mph or anything)

 

man I hope I don't get that mess your going thru. But as for when a hose looks good, it's usually full of pin holes that throw these annoying codes, such as the gas cap and the crapy lil spring that get's weak from running low tanks of fuel a lot then as if you kept the tank 3/4 full all the time. But live an learn as I go

still quite happy with this car even with all the repair's here an there

 

You say you replaced the LDP, but you have an NVLD pump. I'm assuming that's what you replaced (the thing by the RR wheel)? The NVLD is capable of detecting a hole that is 0.5 mm big, so you have to be sure all the lines are good to go. Though, a medium leak is a bit more.

Perhaps by vent valve they mean the purge valve/solenoid, which is in the engine bay? The terms get used interchangeably, so sometimes it's just the wrong term is used depending what the manufacturer calls it.

 

I guess maybe it was a NVLd or whatever. I know I changed the canister and two other parts, which are all the EVAP parts listed in the repair manual. I just replaced the PCV valve anyway, so I guess if the light comes back on after I drive it a few more miles, than I will consider the purge valve/solenoid or whatever. I unhooked the battery cable because I was working on some wiring for my subs and amp and that reset the system so the light went off. I drove about 40 miles today, so I have to drive another 10 or so beforee the light will come back on if something is still wrong with the EVAP system. I know i was getting the code for a small EVAP leak and the code for a med. EVAP leak, and at one time before, I did get the code for general failure of EVAP emissions system, but that code went off a while ago. I will definitely post something when I get it figured out for sure. If I do not get it figured out soon i will have to break down and take it to the shop. Thank you for the ideas so far.

 

I have a CEL currently (one that comes and goes) for a general failure. The two main parts of that are the NVLD and the purge solenoid. I haven't touched either, but one of them is my problem. Since you've replaced the NVLD then, the purge solenoid (vent valve) is likely about all you have left by the sounds of it.

 

ok well ill have to check it out. is there a way i can check it before getting a new one by chance, or do i just need to change it and see if it fixes the problem? i guess if its the only thing i haven't changed that has to do with the EVAP system then so be it.

 

There's a test that can be run using the Dodge DRBIII+, but other than that, dunno.

 

Well so far, I have driven over 75 miles over a period of about 5 different trips, and the check engine light still has not come back on yet, so I am hoping it will not come back on. I can't be certain, but I think it is getting better gas mileage as well. Sure hope it stays off. if not ill have to change the purge valve solenoid next.