Dodge Challenger Forum banner

Replaced Upstream O2 sensors

8K views 39 replies 8 participants last post by  Nuke 
#1 ·
I just replaced the two upstream oxygen sensors on The Bacon Hauler, and I was surprised at the condition of the old ones given the fact there were no codes or anything indicating they were at the end of their useful service lives. And maybe they weren't actually about to take The Big Dirt Nap, but a visual inspection of their condition certainly doesn't instill any confidence in their continued healthy operation after 140K miles of use:

Soil


Auto part


Bow and arrow Arrow Compound bow Ranged weapon Archery


I replaced them with NGT/NGK brand equivalents, and there are no DTCs (yet) that would lead me to believe the car is going to reject them. I have heard this is a risky replacement to do if you don't use Mopar branded replacements, and maybe it is, but NGK is the manufacturer of the OE O2 sensors, so their aftermarket alternatives (NGT brand) should do the job just as well I would think...they have so far anyway.

As far as the level of effort to actually get the two upstream sensors swapped out, I would put that at an 11 on a scale of 1-10. No really, this was the biggest pain in my backside to complete that I have attempted in recent memory. It took me many hours, like 8 or so, spread over the weekend to get it done. And I cannot count the number of times I gave up and started dialing the local wrecking yard to have them come pick the car up and just take it to the crusher. That's how mad I would get trying to complete this seemingly straightforward task.

But I persevered, and despite the considerable number and level of difficulties I encountered, I improvised, overcame, and adapted my way to success! The engine's closed loop operation is tighter in all RPM ranges and its less shaky now at idle when not in gear. So I can tell the car likes the new sensors, and if she likes them, I like them!

Here's to getting another 140K miles out of these ('cause I don't ever want to have to go through that again!)!! :guiness:
 
See less See more
3
#3 ·
Yeah it was mentioned on the HP tuner forum that some aftermarket O2s can cause issues. :dunno:
https://forum.hptuners.com/showthread.php?71393-weird-fuel-issue&p=527395&viewfull=1#post527395

According to this vid, it has to do with how some Chrysler systems use a different bias voltage.

Keep us posted on how they holdup.
Yeah, I'm about to have to take a 7 hour road trip out of town and back any minute now, and I figure that should be a good trial by fire for the new O2 sensors. I mean, if 400 miles of highway driving isn't enough to weed out all non-hackers, I don't know what would be...
 
#6 ·
I imagine that the O2's in my 2002 Durango look the same, I have never changed them out and the truck has 155,000 miles on it...but no CEL and the truck runs fine....I give you props Nuke for taking that job on. I could never do that...just don't have the patience!
 
#7 ·
I blame alcohol for it actually. I had purchased the sensors some time back with the intention of swapping them out, but when I got it up on the jack stands and took inventory of just what all would be involved in getting the job done, I chickened out.

Flash forward a couple months to Saturday night, and as I was cleaning up the garage a little, I ran across a Crankshaft Position Sensor I had also previously purchased but never installed due to the amount of work required (starter has to be removed). I was fully 5 beers into a 8 pack of 18 oz cans, and as I stood there staring at the CCK sensor in my hand, and remembering the O2 sensors sitting on the shelf just beyond it, I thought to myself, "Nuke, buddy, YOU GOT THIS!"

So I pulled her up onto the ramps and jacked it up onto jack stands once again, this time fully confident that I would have a fresh set of sensors installed on the car by the time I went to bed that night.

Well, I ended up passing out a little on my wheel-less creeper pad that night somewhere in the middle of the job. I came to after a while, went inside and went to sleep for real, got up the next afternoon and started in on it again. It took me all the rest of Sunday and into the wee hours of this morning to finally complete the job.

I'm glad I got it done, but I am not proud of the language I used at some points during the install. My most embarrassing string of curse words came spewing forth somewhere in the 2am-ish period Sunday night/Monday morning when I thought I had stripped out the threads on the driver's side O2 sensor bung. I won't put in print what I said to the car at that point, but I will say I accused it of fornicating with swine who had been born out of wedlock to incestual parents that should have been turned into breakfast food if there truly were a god in the sky.

Everything just kinda turned a shade of red after that, and memories actually get a little hazy from the rage I think. But when I came to this morning, the job had been completed, so I guess I figured it all out! :grin2:
 
#9 ·
Yeah, I am surprised they were still functioning well enough for the computer to use for the fuel trim adjustments. I have read that even the slightest contamination from foreign substances getting on the sensor tips could cause them to go teets up, yet these seem to have sprouted their own stalactite (or is it stalagmite?) colonies and still remain in working order.

It makes me really curious about what condition the cats are in...

I'm going to eventually swap out the downstream O2 sensors since they are so easy to get to that I could trip and fall and still accidentally get those downstream ones changed. And I will post up how they look too, as their condition in comparison to the upstream ones should tell me something about the condition of the cats.
 
#10 ·
Yeah they are fun to do, I did all 4 of my o2's about 2 months ago. It took me about 2 1/2 hours on a lift to do them. My biggest problem was getting my big ole meat hooks in that tight spot for the up stream one. Those were a PITA, the post cat o2's were cake to do- 10 minutes tops. It also helps that there wasn't any rust on them either.
 
#11 ·
A lift would have saved me some time and effort for sure, but it wouldn't have made it 'easy' by any means. As you can probably attest, having easier access to the parts only goes so far. If it's in a bad location and/or oriented at an odd angle, you're boned, lift or not.

In hindsight, I would remove the steering column to get at the left side upstream one. That would make it so much easier to get to. I considered doing that last night, but I kept thinking surely this wasn't going to devolve to the point that I had to remove the damned steering column. That would be a major pain to do and add untold time and effort to the task.

Little did I know, it would not add any more time or effort than fighting that sucker the whole time I was trying to get at the sensor on that side...
 
#12 ·
I am lucky that I have access to a lift for sure. I agree the orientation is kinda screwy on the upstream o2's and breaking them loose was the biggest pain. I actually considered removing the cats/ intermediate pipes which would have made access easier but I didn't want to mess with potentially damaging any gaskets.
 
#13 ·
I hit mine with some penetrating oil and let it soak in an hour or so before starting. That seemed to help on the right side one. It broke loose with little effort, once I finally got the socket in place and the two wrenches lined up on it to twist. That part took a lot of effort, but the lube definitely help to break it loose.

The left side was seemingly unaffected by the penetrating oil, which is not surprising since I couldn’t really see it well enough to make sure I got the oil properly applied. Combine that with the fact that I couldn’t get my hand up in there (or down in there either) well enough to get a good grip, and breaking that side loose took exponentially more effort.

I did remove the bolts on the exhaust flanges where they attach to the manifolds just under the sensors, thinking that I would be able drop the exhaust pipes and cats a little to make room. But my exhaust is bolted up to the car well enough that the pipes hardly budged at all. I would have had to loosen it all the way back to allow it to be moved out of the way enough to do any good I think.
 
#14 ·
When I was swapping in the long tube headers I too the old O2 sensors off before I removed the manifolds and midpipes. I don't remember it being that difficult...but then again the header install might have masked the pain. I will say that with long tube headers O2 sensor replacement is a breeze.
 
#15 ·
Unless a sensor fails early, prematurely, and so far with my cars none has, when one goes "bad" -- as was the case with the Turbo when one sensor was tripping the CEL due to a sensor heater circuit fault -- I replace all 4 sensors.

When I had the sensors replaced in my Turbo at 132K miles afterwards the engine ran noticeably better. Kind of surprised me, but highlighted how at least sensors can degrade even if they don't degrade enough to trip a CEL. I think I was fortunate the one sensor did fail which forced me to replace the set when I did.

Might mention the CEL came on as I was leaving a Barstow gas station having just filled up the gas tank after a nearly 200 mile drive from AZ to CA on I-40. This after a 2 day drive from Springfield MO. All the way from Springfield the engine was fine. Even when the CEL came on there was no sign of any engine issues. Every fill as I made my way from Barstow to home the CEL came on. I would read the code and note it was the same code as before, then clear the code and drive on.

Likewise when I had the sensors replaced in my Boxster at around 305K miles (one sensor was causing a CEL but except for recalling the error code pointed to an O2 sensor I can't recall any other details) -- the sensors had around 200K miles on them -- afterwards the engine ran better.


With sensors looking like they looked out of your car's engine you might consider a Techron treatment. A bottle of Techron mixed according to directions on the bottle... well, almost... The bottles I get treat 20 gallons but I dump the entire bottle in a nearly 17 gallon gas tank. Then drive the car as you normally do. As you use up the gasoline with the Techron added you might notice the engine running better as the injector tips, intake/exhaust valves, combustion chamber and possibly even the converters receive some cleaning from the Techron.
 
#18 ·
Si...I unhooked it before removing the starter, so it was unhooked for several hours.
 
#21 ·
I ran across the old O2 Sensors cleaning the garage (I was cleaning the garage, not them...they were just laying there collecting dust...literally) and figured now would be a good time to update this thread with my experience so far with the "non-OEM" sensors I installed.

First and foremost, I have had no driveability issues, DTCs, or Check Engine lights happen to me as a result of using these sensors. So that's obviously good...but what's really good is that I have not been stopped and messed with by the local LEOs at all since I installed these NTK sensors...not a single time!!

Now, they are still messing with me on occasion when they're bored (I assume they're bored; I hope they aren't actively out to mess with me to scratch some sort of perverse itch!).

It's just the same, age-old tomfoolery they keep rolling out though...I'm sure we've all had our share of it...you know, where they follow you for several miles without ever initiating a stop, or they sit across the street and watch you while you wash your car in a local car wash, and the perennial favorite - whip a u-turn and run up behind you real fast when you pass them going the other way. I'm sure everyone has had their fair share of all that...

But I digest...

So, I'm a couple of months in now, and with ~10K miles on them, the two NTK oxygen sensors I installed in the upstream spots are working just as well as the original ones did, even better actually (see paragraphs above)!!

I went ahead and snapped a couple of pics of the box with the NTK part number visible in case anyone wants to give them a day in court on their own cars. Speaking of which, I have one of those coming up...now where did I put that summons...

Nuke, OUT!


Finger Hand Auto part Automotive engine part


Finger Design Hand Nail


Technology Electronics Auto part Electronic device Finger
 
#28 ·
I did a vid on testing them. It is quite easy to do on the bench.

My method to test a sensor if a code is thrown, is to swap the culprit with a sensor that didn't throw a code, then clear the codes. When a code is thrown again, the OBD2 reading will let me know if the code followed the sensor or if the problem is something else, such as wiring. Reminds me that I still need to install my on-board electronic packrat deterrent system...
 
#25 ·
Never bothered to check O2 voltages with the KOEO. The data could be stale. Even if not since the engine is not running there is no flow of exhaust gas past the sensor.

But a number of times with the engine running I've monitored the O2 sensor voltage of both banks. I have never seen both #1 or #2 sensors go bad concurrently. So one has a healthy sensor to go by.

In one case, the first time I encountered a bad O2 sensor, I remember the failure took a while -- around 30 minutes of driving -- and after I saw the CEL on and checked the sensor appeared to be behaving normally.

Only when I got good at guessing when the sensor was going to act up and then observing the sensor voltage did I see the behavior that triggered the CEL. But it was quite a brief event.

After this I just decided to rely upon the car's ECU to flag a bad sensor. So later on when the CEL came on and it was a sensor problem I either replaced the sensor indicated by the error code and its counterpart on the other bank, or I just replaced all 4 sensors.

Now once in a while I did play around with my Actron OBD2 tool which allowed me to initiate some O2 sensor tests the engine controller supported. However, I can't recall any specific instances where the test results clearly pointed to a bad sensor.
 
#29 ·
Good timing on reviving this thread, I’m planning on replacing the two downstream sensors early next week to complete the O2 sensor maintenance I started with the upstream replacements.

I am curious to see if having new ones on the downstream side will help any with gas mileage, though I’m currently doing so well in that area that it’s hard to imagine a Hemi with 165K miles and no MDS getting any better at this point....

I just pulled in to the house from a 5 hour trip out of town, and my MPG meter on the EVIC says I got 26 MPG.

Granted that was under the best possible circumstances - almost all highway, cruise set at 75 mph, 65F ambient temp - but even still, that’s about as good as I’ve ever gotten in that car, even back when it only had 100K miles on it.

I would have expected that to slowly decline over the miles I’ve racked up, but I guess all these sensors I’ve replaced have been keeping things on the healthy side... ?
 
#32 ·
#31 ·
I thought the downstream only get involve in COT fueling and monitor cat efficiency? If so I don't think they would impact MPG.
yeah, seems like I remember running across some info indicating they wouldn’t help MPGs much, which is why I opted not to do them previously with the others. But now that I’ve got just about every sensor replaced I can possibly replace, these two are the only ones left that are original, so they must go, lest my OCD drive me crazy!
 
#40 ·
Well I guess I will find out if they have much effect on MPGs, at least if replacing them on mine does, as I should have them in by Thanksgiving, and thus in place to test out on the 7-9 hours worth of driving I’m sure to do over that 4 day span.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top