I've been dealing with the P0440 code ever since I purchased my truck last August. I have a code scanner and have been resetting the the light all along, but this time I left the CEL on for over a month. Yesterday, when I read the codes, P0456 was a new addition.

Months ago, I purchased a new gas cap from the dealer and checked the evap system hoses to no avail. Furthermore, my records from the previous owner show that he had a smoke test done over a year ago, so I'm thinking it's not the hoses. Yesterday, I double-checked them with a mirror and saw no cracks. I also zip-tied all the ends.

So now, I'm starting to think it might be the leak detection pump. Also, I followed a hose from underneath that led me to a round device which sits in the front driver's corner, at roughly the level of the battery tray. I'd have to remove the battery to get to it. As far as I know, the LDP is the device which sits next to the canister underneath so I'm not sure what the other underhood device is or does.

Anything else I might need to check? Anyone had any luck with aftermarket LDPs? I've seen them cheap as $25 online. Dealer price is $150.

Thanks in advance.

 

P04xx codes can be hard to fix because there are a lot of causes for those types of codes. Without a smoke test it is trial and error unless you find an obvious broken part or damaged emissions hose.

The round device in the left front corner is your charcoal canister purge solenoid. You can test it by removing it and if you can blow air through it it is stuck open and should be replaced.

The ldp is mounted on the bottom side of the battery tray. You have to remove the battery and unbolt the power distribution center, prop the pdc up out of the way so you can remove the battery tray. There are 2 emissions hoses on the ldp, maybe one has a crack or split. I had to replace my own ldp a few years ago because I was hit in the left front bumper area in an accident. The wreck damaged the ldp but my code was p0442. It did not throw the code until 2 days after I got my truck out of the body shop. I used a ldp from a "cash for clunkers" Dakota at the junk yard, it only cost $20.00 and has been working fine for almost 4 years now. I personally do not trust ebay parts. A lot of them are cheap junk. I also replaced all of the emissions hoses in my engine compartment with about $10.00 worth of fuel line. I replaced the right angle hose at the purge solenoid too, the parts store had those for just a couple bucks.

I hope that helps you. Those p04xx codes are hard to trace down.

Jimmy

 

Wow, so I was mistaken in thinking that the LDP was underneath, near the charcoal canister? I guess this thing is completely hidden then? As soon as I get home, I'm going to remove the battery and tray. Hopefully, I'll find a busted hose there. When you installed the junkyard LDP, did the CEL clear on it's own or did you have to clear it?

Thanks, Jimmy. You've been a big help.

 

I stopped by Advance and they cleared the code for me with a code reader. You can also clear codes yourself by disconnecting the negative battery cable and holding the ignition key in the start position for 30 seconds. That is called a hard reset and will clear all stored and pending codes from the pcm. Not long ago I bought a code reader at Harbor Freight. Regular price was about $120.00 but it was on sale plus I had a 25% off coupon so it only cost me $60.00. It reads live data and sure has come in handy lately when I had problems with my catalytic convertors and O2 sensors.

The hoses at the charcoal canister are known to rot out and crack. Even though you checked them already it might be worth it to just replace them anyway. It's possible there is a split or crack you can not see.

 

I was asking because sometimes CELS will clear on their own after a fix is implemented, which is proof in the pudding that it actually worked.
I have a code reader which I bought on Amazon for $20. It does the job well and I've just been clearing the codes around once a week or so. I will reset the system as you described. Can't wait to see what I will find under the battery tray.

Thanks again

 

also, there's a form fitted U-shaped hose back there I haven't been able to track down. 1/2" at one end and 5/8" or something like that on other end.

 

The hose from my LDP leading to the intake manifold was like that, a different size at each end. I just used two sizes of hose and a tee adapter with the same two I.D. sizes and made up a hose to fit. I wrapped the teed section up with several layers of electrical tape to seal it off, and it has been working like a champ ever since. Dodge has a lot of odd hose sizes and odd shaped hoses. I had to buy my new PCV-to-manifold hose at the dealer.

Jimmy

 

Well, I didn't get started till late last night, so I didn't finish pulling out the battery tray. Seems like it's going to be a little more involved than I thought, so I'll finish up tonight.

Took a pic of the tray (click below). I guess the purge solenoid is the bottom two of those round canisters. Any idea what the top one is for? It's the one with the screwdriver pointing to it.

20140113_212935.jpg

 

The top one is the purge solenoid. It is the one with hoses on it. The right angle hose connectors are replaceable. I don't know what the other round part is. I mighy be able to figure it out by checking my truck and manuals but am at work right now. It looks like it may be part of the battery tray.

Jimmy

 

It's a canister - the lower one that has all that white stuff on top. I'll take a better pic of it later. I'll blow through the purge canister too as you suggested. Looks like two hoses coming off it. Blow through bottom or top? Will I get high?