Disagree. While those numbers may be correct, I wouldnt change them until they throw some kind of code. An electrical part generally either works or it doesnt.

 

I've found that buying the o2 socket for around $10 is worth it's weight in gold when you encounter a stubborn sensor.. It's the only dang thing you'll need it for, and once every- what, 150k miles or so? but dang- it makes short work of removing stubborn sensors..

look behind your exhaust manifolds/headers.. if there is a football looking bulge right behind the collector assembly, chances are you have cali emissions.. To my knowledge, cali's are the only ones w/ pre-cats.. and word to the wise: yo really don't want to damage a pre-cat.. those dang things are $$HIGH$$...

 

o2's have also been known to NOT toss a code, appear functional to the PCM, yet still not be operating at peak efficiency.. which robs you of proper fuel trim, which cost you $ in economy.. The effed up thing about it is once you tear open the package, you ain't gettin' your $ back for it, and that negates the option of removing the old ones and trying a new one as a test.. just to put the old back in and return the new one..

I'd wanna be certain the thing is bad- and a code will do just that, but just because it isn't tossing a code doesn't mean it is operating at peak..

 

--- depending on year you will have 3 o2 sensors. two which are pre-cat and one that is post cat (sometimes installed in to the cat its self) but most of the time its is in the mid pipe about 6 inches after the cross member for the tranny. As far as kinda you can go to your local advanced or autozone and order an oem style for 50 to 100 bucks. i wouldnt requiment running the universal on the dodges they dont like them. One thing people dont know is that dodge motors mostly the 318 and 360 under perfect running condition can run without a cat and not have a MIL activation. the rear o2 sensor is far enough back in the mid pipe to allow full burn off to read propery for emmissions. also i would check the battary connection both on the battery side and starter and ground sides. the dodge computer cant send pulse to the alt to allow charging this will also drop pcm memory and cause a stalling at idle. (more common on dakota but also on rams as well) as far as load up. i dont see a clogged cat causing that normally due to the style of exhaust clamps between the down pipe and the manifolds if the cats clogged it causes a destince whisling sounds that never goes away and power loss is huge. most of the time wont even allow for more then about 45 to 50 mph under wide open condition. if i had to take a edcuated guess i would say to check the cap and rotor plugs wires and do a compresion check. i would also look in to and just for ****s replace the intake base gasket (unless you have already done so) i would also get a hold of hughes and get there base plate kit it isnt steel like that stock one so it will expand at the same rate as the intake.

 

FAIL. Oxygen sensors at end of life give up crappy waveforms but don't go open or short, and it's rare for a DTC to be set before the driver complains of lost performance and fuel economy and usually very low idle with "a sucking noise".

We go round and round on this pretty regularly.

 

Yup, oxygen sensors tend to not operate well towards the end of their life, throwing off power and MPGs, and won't throw a code until its gets so terrible that the PCM has a hard time keeping the vehicle running (usually).

Oxygen sensors aren't like a circuit thats on, off, or busted. They send varying voltages back to the PCM. Anything with variable voltage can be wrong, but not generate an error code. (TPS, IAC, MAP, for other examples.)

Federal emissions will only have two. One pre, one post. Depending on model, they are in slightly different locations, but in the 2nd gens, we've never had more than two for Federal emissions.

Cali trucks, as others stated, are different, and will have more than two.

 

That's what I don't get. I have a born and bred Cali rig and I only have 1 pre and 1 post O2 sensor.

 

I'm sure someone will correct me if im wrong, but I believe dodge kept the 2 sensor setup until 98, which is when (or near when) C.A.R.B's stricter emissions went into effect IIRC

Guess mine are the exception to the rule then. Fuel economy leaves something to be desired (but I dont expect much with my 20lb foot), but I have none of those other symptoms at 177k.

 

Thanks for all of the input so far everyone. I can also see how these threads easily get off of topic. Here is a quick update and a little opinion input. First of all, the 2001 Dodge Ram 1500 3.2L trucks, non-California (all other 49 states or Federal Emissions) trucks have 2 oxygen sensors. I verified this by contacting my local Dodge Service Dept., checking in my Haynes manual, and getting under my truck and looking. Most on this forum have also said the same. The only ones that have three 02 sensors are the California emissions trucks, 2 pre and one post CAT. I ordered NTK and the part numbers are as follows:
pre-cat: A/T (automatic transmission) exc.calif: 23139
post-cat: A/T exc.calif: 23140

Also, I would like to clarify the following fact. Too many people depend on codes for determining correct diagnosis. Failed sensors do not always kick codes! You should be thankful if you get a code because this is not always the case. See my other thread about my transmission and governor transducer and solenoid. Just because there is no code does not rule out a problem, especially with sensors.

Yes I am sure that my plenum gasket has not failed, that was one of the first things I checked for when I bought the truck. If an o2 sensor fails, it can cause CAT failure. If my CAT is clogged, I will replace it. For now, I am starting with both o2 sensors. I should have them within 3 days and I will post the outcome. I have already sprayed both fittings with penetrating oil so they shouldn't be too hard to take out. I am planning on replacing my entire exhaust system from the headers back. I have priced a direct fit magnaflow CAT set up for around $416 which includes both exhaust pipes, and CAT. I am going to put a Flowmaster 40 series muffler with 3" exhast ($225) from the CAT back. I will take some quality photos of this entire process to help others in the future and to show there are only 2 sensors on this model.

I would put money on it that my truck runs alot better with just the new 02 sensors.

 

Thanks to all on the forum. I have 2001 dodge ram 1500, 5.2 L, 67,000 miles, no California emissions, pre and post o2 sensor. Not a mechanic but not afraid to get my hands dirty. Had problems on start up. Engine checked out find on computer, no error codes. Someone somewhere said wires could be bad on O2 sensor. Moved the wires on the pre cat o2 sensor and truck ran find. Moved wires again and truck ran bad. It appeared to be bad wires. I was given a denso #234-4769 for replacement it looked similar (internet search also showed this to be the one) but was off on the housing of the plug. Needed #234-4653. It fit and corrected problem. Thanks to the mechanic across the street all is fixed. Recommend anyone who is not a mechanic to be careful. Removing the sensor can be tough. Use heat and get the correct socket. Can't see the connection so you have to feel your way. Be careful putting it back. He took it very slow. After almost 11 years and 67,000 miles things went well. Thanks to all on the forum who helped me figure this out.