Hello all, and thanks in advance for any help y'all can offer.

I have a 2005 Dodge Neon SE 2.0L with about 125K miles on it. Got this car in late '06 with 50K on it, and have had little or no trouble with it whatsoever.

In Apr. 07, the check engine light popped on. Thought I had got some watered-down fuel (gas around here was like $3.75/gal then, so who knows?) but I took it to a local service center I trust. He said he thought there might be a leak in the fuel system, that the error had to do with low pressure in the fuel system. He wanted to run some kind of "smoke" test on the fuel system, to the tune of $250. I just didn't have that at the time, so I let it go. Probably dumb, but I'm happier dumb than broke.

Anyways, this check engine light has been on since then ( YES, 3 years). I've had no other problems with the car ( other than a dead battery ), and I keep the oil changed. Just today, I got curious about it again, and figured out how to get the display to tell me the error code (Ignition on,off,on,off,on) and it is P0499, which through some web searching leads me to a string of big words like "Evaporative Emission System Vent Valve Control Circuit High".

Just bought a new gas cap and it seems to tighten fine - light still on. Where do I begin with this? And in addition, have I been lucky that other things have not cropped up, or can I keep driving with this error indefinitely? What symptoms/damage might this cause if left unchecked? Any insight you can offer will be greatly appreciated.

 

Everyone seems to think a new gas cap is the solution to emissions codes...


More likely than not, my guess is it's the NVLD. They go out on these cars. Pretty easy to DIY. Can be bought new or picked up at a junk yard or recycler. Also, being at 125,000 miles, have you had your timing belt, water pump and tensioner changed?

 

I changed the gas cap because everywhere I looked, that was the FIRST thing everyone wanted to check - and it's idiot-proof to change. Thanks for the info on that NVLD. I understand about the junkyard, but am having trouble identifying/finding a new one at local parts places. What do they run new?

And no, I have not had the timing belt, water pump, or tensioner changed. Are these things that could potentially fail soon, based purely on the mileage? This is approximately $200 just in parts. I can probably change all three myself. Why is this necessary?

 

Point proven.

No idea, haven't actually replaced mine. If I had to guess, since it takes about 10 minutes to change, probably in the ballpark of $75? That is going to be a dealer-only part, especially since it isn't a "normal" wear and tear item. No point for aftermarket companies spending the money to make the part if only one person here and there might need it, from a logical and profit-based point of view.

Yes, they should be changed at around 105,000 miles. If the timing belt breaks, you will have to buy a new head for your car too. The Neon has an interference engine (you can Google that for a description). The water pump should be changed too (it can go out), but isn't listed in the service schedule, so while all that labor was spent to get in there, might as well change it and save a headache and all of that labor later if it were to go out. The tensioner, well, they wear after 105,000 miles. RockAuto has the complete kit (belt, water pump and tensioner) for $100.

 

Yeah I get the engine light on for my NVLD intermittently, just have someone reset the codes, and it'll be back in a few months.

 

You don't even have to have someone do it. Just pull the negative battery terminal for 5 minutes.

 

Yeah or you can do that lol but it'll be back though, it's nothing to really worry about unless you want to pass emissions.

 

All I know is, the next time I get the code for the NVLD (P044X IIRC), it's getting a "love tap" with my 1" wrench. See if that fixes it...