hey all, long time since i logged in here! i'm having a problem that i think may be my heating system, but i'm not sure... i've been smelling a propane/natural gas smell coming from my vents for the last couple of weeks. it started out very strong, but it seems to have resided a bit. i can still smell it when the vents aren't running, but if i turn the air on it seems to dissipate. what could this possibly be? i've had several people tell me that it has to be the cat. converter, but the truck isn't throwing any codes besides the two i've had for years.

the codes the truck has been throwing are P0456 and P0440, had those for several years now, nothing has ever come of them.

 

Umm both of those Codes are for the EVAP system which can exhibit smells of gasoline and/or exhaust fumes when to some people smells similar to Propane/CNG.

Start checking your entire EVAP system & Vacuum lines... those problems are a pain to find, so good luck...

 

so what does the evap system do? i've had those codes literally for years, why would it take 4 years for them to suddenly become a problem?

 

it does a lot of things, but it is keeping your fuel system pressurized. Those codes could be as simple as a fuel cap gone bad, or as crappy as a line rusted through under the fuel tank if you're really unlucky. Hammer has an evap system diagram posted in the faq diy section, take a look at that. You can start by the solenoid and visually check for signs of a leak. If' you're lucky you will see something that you can replace. If you're unlucky and don't see something you can try replacing the gas cap, if that doesn't work you may have to get it smoke tested to find the leak.

As to why it took so long to do something, well it's a leak, so obviously it finally got bad enough you can smell it.

 

Ewing is right on, Look at the diagram from Hammer it helped me alot.
After you figure it out get under your truck and the black canister next to the gas tank has two cheap rubber lines coming out of them, inspect them for holes or cracks. that is usually the fix

The P0456 is prolly going to be a gas cap
P0440 is prolly the lines

 

ok, i've forgotten how to find the FAQ DIY section, can someone help me out?

 

really? its just above the general discussion section... anyways here's the link you need

https://dodgeforum.com/forum/3rd-gen...m-diagram.html

happy hunting. If you find it be sure to post back, it's a common problem and it helps other guys out to see how someone solved it.

 

If you stick to looking in the TECH section you will find the Fixes to your codes.