I'm hoping y'all will give me some great info before I take my truck (2001 Quad Cab SLT, 3.9L, 6 cyl) to the garage so I'll look like I know what I'm talking about.....

I had a P0442 code and I read on this forum it could be the gas cap or a leak in the gas lines. I replaced the cap and did my best to check for leaks but found none. I reset it and now the code is back along with P0138 (02 sensor). Being a woman, I'd like to know what I should say to the mechanic so no more is done to my truck than needs to be done. Unfortunately my husband passed away so I get all my help from this forum!!

THANK YOU, very much, for any help, info, instruction you'd send my way!! I hate taking my truck to the garage as it is but it will be alot easier if I know what I'm talking about.

P.S. How many 02 sensors does this turck have?

 

The P04xx codes are for evaporative emissions system leaks. It can sometimes be as simple as needing a new gas cap to fix it. I have heard that the aftermarket gas caps don't do well on Dakota's and you can still have the code even with a new aftermarket gas cap.

One thing you can do before you head out to the garage is look under the truck, just in front of the gas tank on the driver's side, there is a black evap gas vapor canister there. It has charcoal in it and it's job is to capture excess gas fumes from the gas tank. If you or a previous owner had been topping off the tank when you fill up, that is to say continuing to pump gas into the tank after the gas pump nozzle cuts off, it will ruin the charcoal canister. But the main thing to look for at the canister is there are 2 rubber hoses that are formed hoses with a curve in each one, they go from the canister to the hard plastic evap hoses running toward the engine. Check those curved rubber hoses very carefully and look for cracks, splits and deteriorated rubber in the hoses themselves. Dakota's are sort of known to have problems with those hoses, especially on trucks up north and in the midwest where there is salt and chemicals on the road during the winter. If the hoses are damaged, you ought to be able to replace them yourself cheap with parts from the Dodge dealer or make something up to fix it with hoses from a parts store. A good parts store will help you find what you need to replace the hoses.

Check the rubber emissions hoses up in the engine compartment too. Sometimes you can find a bad hose by sight, replace it, reset the PCM and that fixes the problem. The garage will have a smoke machine they use to inject smoke into the evap emissions system to find leaks. That makes it easier for them to fix the problem faster for you.

Your truck has a total of four O2 sensors. There is one in each exhaust pipe in front of the catalytic convertor, and there is one after each catalytic convertor too. The sensors after the catalytic convertors (they are called the downstream sensor) don't do anything much. The ones before the catalytic convertors (upstream sensors) are the ones you need to focus on. These are the sensors that tell the PCM what the exhaust oxygen content is doing so the PCM can adjust for the right air-fuel ratio. O2 sensors can get lazy and they do wear out once they get up around 75,000 miles. If your truck has 80 or even 90,000 miles on it, it may be a good time to just replace the sensors. And that is something you could probably do for your self and save some money. I replaced my own upstream O2's at 85,000 miles. I used new parts from NGK and bought them off their website www.ngk.com and both sensors shipped only cost me about $65.00. They are a bit tricky to get to and it is easier to get them out if you have the special socket for it, about 12 bucks at a parts store or 6 bucks at Harbor Freight Tools. It may be better for you to pay the shop to do it, being up north yours may be siezed in place from all the salt and road chemicals. If the garage says you need a new O2 sensor, it's probably best to replace both. If one is bad, the other one can't be far behind. Just don't let the shop use Bosch O2's, they don't work well with the 3.9. Tell them you want NGK or an OEM Mopar O2 sensor. NGK is the OEM supplier for Dodge anyway. One way to tell if your O2 is bad is if you have recently had an unexplained drop in your gas mileage. A bad O2 can cause poor engine power and performance too, but a bad O2 sensor does not always set a trouble code and/or trigger the check engine light.

Good luck and let us know how it turns out.

Jimmy

 

here is what the canister looks like

 

Thanks, 01SilverCC, for all the info and especially for the picture of the canister!!! I'm a female and I'm willing to do whatever I can myself but I usually don't know where to find stuff. I love learning if someone is willing to help me out!!!

I will check the hoses attached to the canister. Not sure which ones I'm supposed to check near the engine??

When I was looking under the truck about a month ago, I only saw one CAT. Did some of the 3.9's only have one? If yes, how many 02 sensors would I have with just one CAT and which ones should be replaced along with the P0138, bank 1, sensor 2? I want to know exactly what to do with them before going to the garage next week. I doubt I would be able to change them out although I wish I could!!! I'm trying to find someone around here who might slide under there and do it for me.

Thanks, again, for all of your help!!!!!! I appreciate it more than you could know!!!!!!

HAPPY NEW YEAR!!!!!!!!

Laurie

 

There should be one cat and 3 O2 sensors, 2 of the sensors are before the cat and one after the cat. Also, in the picture above, the two arched tubes to the right sie of the picture are the ones that need checked.

 

Thanks, Cowboy63645, for your help!!!! I truly do appreciate your taking the time to send me the info and, because you know what you're doing, you couldn't know how much it means to me when the people on this forum take the time to help me out!!!! I'm a female so there are lots of things I'm not able to do when it comes to my truck but I like to learn about it and do whatever I am able to do myself. Of course, there are some out there who don't want to help a female so the help from people like you, 01SilverCC and many others is priceless to me!!!! I've saved $$$$ and learned to work on my truck because of you guys!!!! With my husband's passing, I'm really in need of help with the truck!!!! He was the one who did all the work on it and, if he wasn't able to do it, at least the mechanic wouldn't take advantage of him because he knew what he was talking about. So, THANK YOU!!!!

P.S. You might want to check out my new post "Smell Coolant"

HAPPY NEW YEAR!!!!!!

 

Your welcome, and that is what the forum is here for, to help others understand problems, and for some other members, to show off there trucks a bit!! You being a female has nothing to do with not having the ability to wrench on your own truck, I know women who can out wrench me any day of the week! Get a small tool kit, a repair manual, and start doing little things like tune ups and oil changes and checking fluids to get comftorable with your vehicle. Before you know it, you will know more that you thought about your truck and put some of the money hungry mechanics to shame!! Be safe and I wish you luck with your truck! Happy New Year!!

 

Yes, Cowboy63645, I have learned alot on this forum!!!! I can change my oil, clean my throttlebody, clean sensors, check/refill fluids, etc. but I'm not good when muscle is needed. I've got some muscle, don't get me wrong but, at 50, not as much as I need for the bigger jobs. I do love to learn about my truck and I love working on it and taking care of it!! My problem is finding the right hoses, parts, sensors, etc. If someone sends pictures, that's awesome for me because I do great with a picture. I really enjoy working on the truck and I get this from my dad who was a Master Mechanic. I've always had a mechanical side to me.

So, thanks, again for all your help and direction!!!!!!! I can't tell you enough how priceless it is to me!!!!!!!

 

Let's see....50, woman, works on cars, has the ability to use an online forum correctly....

You wouldn't happen to be related to this woman, would you?

 

No offense intended Cowboy but her 2001 Dakota with a 3.9 will have 2 catalytic convertors and 4 Oxygen Sensors. I have a 2001 with a 3.9 and it has an exhaust pipe for each cylinder head and exhaust manifold. The exhaust pipes run under the truck on either side of the transmission and right on either side of the tranny there is a donut gasket, the upstream O2 sensor then the cat and finally the downstream O2 sensor. Then the left side exhaust pipe crosses under the tranny, over to the right side of the truck and the 2 pipes join together and mate into one pipe just before the muffler. The muffler and tail pipe are the last parts in line on the exhaust system.

Bank 1 is the exhaust pipe on the driver's side of the truck. Sensor 2 is the downstream sensor. It is odd that sensor would be bad but P0138 indcates too high of a voltage input to the PCM from that sensor. So Luvdogz may be able to just replace that one sensor, do a hard reset and clear the code for it.

For the emissions hoses under the hood, look low on the firewall to your right of the throttle body as you look at the engine from the front. You will see a large hose about an inch in diameter and a smaller hose running together, they are taped together and come out over the left side valve cover, over the oil fill cap. These are the emissions hoses that run all the way back to the evap charcoal canister back in front of the gas tank. You can follow the hoses where they go, the larger one goes down to the evap leak detection pump which is mounted under the battery tray, the smaller one goes to the purge solenoid between the battery and the inner fender well. There is another smaller emissions hose running from the leak detection pump to a vacuum connection on the front of the throttle body.

The way the system works is every so many minutes of engine operation, mine does it every 70 minutes, the PCM will command the leak detection pump to check the emissions hoses and components for leaks. It will check for evap system leaks right after a cold start too. The purge solenoid does exacly that, it purges any emissions gases and/or fuel vapors in the lines and in the charcoal canister into the intake manifold to be burned and sent out through the exhaust pipes.

The hoses go in several different directions to several different components. If you can follow the hoses and find an obvious cracked or split hose you might be able to repair or replace that hose or section of hose. If there are no obvious problems with the hoses, that is what the shop uses the smoke tester for. It locates leaks when you can see the smoke leaking out of whatever hose or part is damaged, just like when you put a flat tire in water and look for the air bubbles to find the hole or nail in the tire. There is an evap test port with a green cap on it inline on the smaller emissions hose, right near the Power Distribution Center. That is where they connect the smoke machine.

You could have a problem with the evap purge solenoid, or the evap leak detection pump, but my guess is there is a leaky hose somewhere. I went through a similar problem on my Dakota back in April. I was in a wreck, it did $4,035.00 in damage to my truck. Two days after I got my truck back from the body shop I had code P0441 come up for a small emissions leak. I tried a new gas cap, code came back the next day. I found a couple of cracked and split emissions hose ends, fixed them and the code came back again. Then I started thinking, the at-fault driver hit me hard enough to break my battery tray, and that may have been hard enough to break my evap leak detection pump too. A new pump at the Dealer is $129.00 and it's a dealer part only. I didn't want to spend that kind of cash and still not have it fix the problem, so I bought a used pump from a Cash for Clunkers truck at a local junk yard for 20 bucks. I installed the used pump and replaced all my emissions hoses under the hood with 7 feet of rubber fuel line hose from Advance Auto Parts and also replaced the double right-angle hose fittings on my evap purge solenoid with parts from Advance. I left the larger emissions hose alone, it looked like it was in good shape and it's a dealer-only part too. I replaced the hoses from where they join up with the 2 hard plastic hoses at the firewall, coming up from the charcoal canister. I only spent 20 bucks for the leak detection pump and less than 20 bucks for all the parts I got at Advance. I did a hard reset on my PCM and cleared all codes out and my Check Engine Light has not come back on since then. Luvdogs, to do a hard reset on the PCM all you do is disconnect the negative battery cable and hold the ignition key in the start position for about 30 seconds. This will clear all codes stored in the PCM. Or you can use a hand-held diagnostic scan tool to clear the codes. Advance and Autozone will read and clear codes for free.

Here is a link to my post from back in April when I had the P0441 problem:

https://dodgeforum.com/forum/2nd-gen...591-p0441.html

I don't mean to sound like a know it all. I sure don't pretend to know everything there is to know about Dakota's but I do know about the evap emissions trouble codes. There are a lot of reasons you can get those codes and you have to start with the obvious causes first. I hope this helps Luvdogz get her truck fixed without costing too much money, especially here right after Christmas. I know what it is like to have a problem and need help with it. I needed a lot of help with a lot of different problems myself after my wife died.

Hope this helps.

Jimmy