When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Today I tried to replace both of downstream O2 sensors on my RDX 2015. The one close to the front of the engine was quite easy. But then when I loosened the second sensor on the back I noticed that its harness is almost unreachable. I could not even spot it from the top of the engine let alone access it. From the bottom, there is no way one's hand can reach it. I also tried a 14" long needle nose plier but there is not enough space for the plier to work or even reach the harness.
I am interested to know from people who have been able to reach and remove the harness on their vehicle or practical suggestion/techniques to do so. Thanks.
To be a bit more specific, I am pointing to the downstream O2 bank 2 sensor (#17 on the below diagram) with the long wire. How do I reach and remove the harness?
I am interested to know from people who have been able to reach and remove the harness on their vehicle or practical suggestion/techniques to do so. Thanks.
It is very helpful to have long automotive picks available in these circumstances.
As you can see in the picture below the 'male' end on the o2 sensor connector has an area, at the top, which usually is fastened to the 'female' end connector of the engine wire harness.
Even though access is very tight sometimes it is possible to either disconnect the female connector from the body bracket that it attaches to & then attempt to disconnect the actual sensor connection (red) as it is freed up in mass.
Long right angle picks are usually handy at trying to manipulate these PIA's.
Also, put a light at the bottom of the work area, shining upwards, then go back up top and see if there is something easily removed, in the engine compartment, that could give you easier access to get at the connector from above?
Good Luck!
It is very helpful to have long automotive picks available in these circumstances.
Even though access is very tight sometimes it is possible to either disconnect the female connector from the body bracket that it attaches to & then attempt to disconnect the actual sensor connection (red) as it is freed up in mass.
Long right angle picks are usually handy at trying to manipulate these PIA's.
Also, put a light at the bottom of the work area, shining upwards, then go back up top and see if there is something easily removed, in the engine compartment, that could give you easier access to get at the connector from above?
Good Luck!
Good suggestion! Actually I do have long strong picks in my arsenal but did not cross my mind to use them. However, removing the harness is one thing, installing the new one in that tight space is another because that certainly can't be done with a pick. I have a fiberglass fishtape that I'm going to send up to the engine bay to locate the harness from the top. Not sure if these all work but they are certainly some ways to go for now
Why are you replacing them? I could be wrong (someone jump in if I am), but these sensors don't provide any engine tuning input. They are only indicative of the health of the catalytic converter immediately upstream. I've never replaced these. Are you getting a catalytic converter code? If one or both of your cats are bad, I would pay a shop to replace them along with the sensors as this is not a small job.
The O2 sensors upstream of the cats provides the ECU with information used to adjust air/fuel ratios' for engine performance. I do proactively replace these between 100-125K miles even if no codes for these are showing up.THese are easy to get to.
Why are you replacing them? I could be wrong (someone jump in if I am), but these sensors don't provide any engine tuning input. They are only indicative of the health of the catalytic converter immediately upstream. I've never replaced these. Are you getting a catalytic converter code? If one or both of your cats are bad, I would pay a shop to replace them along with the sensors as this is not a small job. The O2 sensors upstream of the cats provides the ECU with information used to adjust air/fuel ratios' for engine performance. I do proactively replace these between 100-125K miles even if no codes for these are showing up. These are easy to get to.
I don't have any fault codes. Just want to replace them as a preventive maintenance. Given the vehicle is 10 years at 100K miles now, thought to replace all 4 sensors together.
Yes I could have passed on the downstream ones but I prefer preventive maintenance as given I do it myself, just the cost of part justifies for me. I also like to prevent any possible issues with the yearly emission test. Anyway, have replace 3 of them but the last one gives me a hard time as I cannot remove the harness. So I may give up on this one and try to sell the part on Facdebook!
"Manufacturers recommend replacing O2 sensors in pairs (both Upstream or both Downstream). An older, slower sensor can cause an imbalance in the engine management system, leading to poor fuel economy and possible damage to the catalytic converter."
which makes sense to me. Since I replace one of the downstream sensor I must find a way to replace the other one too. I am surprised that the harness does not come apart from each other. May the engine heath has somehow glued them together. Anyway, the saga continues
I can tell this is bothering you. I had the same problem with an O2 sensor (upstream of the converter) on my wife's Toyota Sienna (rear bank) years ago. I couldn't get to the connector. I took it to a shop and let them do it. I don't know what tricks they used but they do this for a living.
Just be careful, if you screw up the connector, your saga just got worse and more expensive. Good luck.
Even though the above and below are for the easier upper O2 sensor, there should be a similar connector mounting bracket (red arrow) somewhere
for that longer wired downstream O2 bank 2 sensor.
If there is some way to disconnect the whole O2 sensor connector from that bracket, then you should have enough room for the O2 wire disconnection (yellow) as similarly displayed in the graphic.
I can tell this is bothering you. I had the same problem with an O2 sensor (upstream of the converter) on my wife's Toyota Sienna (rear bank) years ago. I couldn't get to the connector. I took it to a shop and let them do it. I don't know what tricks they used but they do this for a living. Just be careful, if you screw up the connector, your saga just got worse and more expensive. Good luck.
I finally got to the connector. My issue is that I am not able to separate them. This is strange. Am not sure but may be the engine heath has somehow melted the inner plastics that they stick so hard.
But as you mentioned, I am careful no to damage the harness. I just wanted to avoid the cost of a shop removing it but I guess it becomes inevitable at this point.
there should be a similar connector mounting bracket (red arrow) somewhere for that longer wired downstream O2 bank 2 sensor.
Actually there is a bracket but the bolt is soooo hard to reach. I am very well equipped with any type of tools at a pro mechanic level but none worked!
Originally Posted by zeta
If there is some way to disconnect the whole O2 sensor connector from that bracket, then you should have enough room for the O2 wire disconnection (yellow) as similarly displayed in the graphic.
The problem is that bracket is not only tied with a bolt it also is connected to another wire from other non-related component. The space is so incredibly tight that removal of it is daunting. I know there must be a way otherwise the shops wouldn't be able to remove it either but I simply don't know how.
Today I finally was able to remove the entire sensor and install the new one. Basically, I first removed the old sensor from the cat, then with a large and long pry bar loosened all 3 zip tie holder from the bracket thus the whole sensor got loose. This gave me much more play ground to try the harness and connector from top the engine toward the firewall. One very important point is that the harness has to be removed with a think flathead screw driver to push on the lock on the back of it. Previously I was trying to push a plastic on the connector body (like the other sensors) to loosen it but it was wrong. Not sure why this sensor is different. Anyway, this completes my saga of replacing all 4 O2 sensors (2 for upstream and 2 downstream) at 10 years 100K miles. So for the rest of vehicle's life I don't have to worry about them
Today I finally was able to remove the entire sensor and install the new one. Basically, I first removed the old sensor from the cat, then with a large and long pry bar loosened all 3 zip tie holder from the bracket thus the whole sensor got loose. This gave me much more play ground to try the harness and connector from top the engine toward the firewall. One very important point is that the harness has to be removed with a think flathead screw driver to push on the lock on the back of it. Previously I was trying to push a plastic on the connector body (like the other sensors) to loosen it but it was wrong. Not sure why this sensor is different. Anyway, this completes my saga of replacing all 4 O2 sensors (2 for upstream and 2 downstream) at 10 years 100K miles. So for the rest of vehicle's life I don't have to worry about them
Nice, just to put a picture to it, the 3 zip tie holders the #17 items on your graphic below?
Nice, just to put a picture to it, the 3 zip tie holders the #17 items on your graphic below?
Yes those are the 3 zip tie holders and two of them are buried deep on the side of the engine and very hard to reach by hand. The best tool is to use a long pry bar and if necessary you can push hard to break them loose. Installing the new sensor is easier as you can just push those new zip tie holders in the bracket either by hand or a long nose plier.
Hi Emry, I am trying to change both CATs on my 2007 RDX and I am having the same problem as you with the hard to remove harness, I think there might be a typo in your post. Did you mean to say work from the top and "pry toward the firewall? Did you have to remove anything from the top of the engine to gain access. I think I know how the connector works as it looks like the same connector used on the warm up cat. WUC. Did you wind up using long picks?
Any help you can give me will be greatly appreciated as I am just a handy guy and not a pro mechanic. I was able to download the RDX service manual or I never would have attempted this.
Yes those are the 3 zip tie holders and two of them are buried deep on the side of the engine and very hard to reach by hand. The best tool is to use a long pry bar and if necessary you can push hard to break them loose. Installing the new sensor is easier as you can just push those new zip tie holders in the bracket either by hand or a long nose plier.
Hi, could you be a little more specific on how exactly you removed those 3 zip tie holders with the pry bar please? Did you reach them with the bar from underneath the car, or from the top? I was trying to do this exact same job yesterday, I successfully removed the sensor from the pipe and disconnected the harness on the top, but then I got stuck with removing those plastic holders… I was able to remove the bottom one(closest to the sensor) of the three, but the other two seemed nearly impossible to get access to without lowering the engine…
I know this thread was posted a while ago now but any inputs would help at this point, thanks a lot in advance…
Thanks for this thread, emry. It was my main source of info when taking this task on.
Here is what I put in my thread:
Success!
Here are the tools I used:
- 3/8 breaker bar - 3/8 torque wrench - 3/8 extension (about 5-6 inches) - O2 sensor socket remover (special socket, required) - Auto picks (get the longest reach you can find) - Long reach needle nose pliers AND long reach 90 degree bent nose pliers) - 18-inch flathead screwdriver - As many work lights as I could possibly find. - Headlamp - FYI the zip tie clips are part number 36538-RDM-A01 and they are super expensive. $11/each after shipping. No dealer in the country stocks them.
As emry had mentioned in his thread, the three zip tie clips are a PAIN. I got the first two off relatively quickly.
- The first zip clip is simple to remove. - The second is tricky. I was able to get it off with an auto pick that was “hooked”…not a 90 degree one. I wish mine was longer. But you want to get the plastic latch that you CANT see first. Once you get that one, you can press on the latch you can see and wiggle it free. - The third clip is my mortal enemy. Don’t even try to remove it. I had a pry bar, but it was too thick. So I used an 18-inch flathead screwdriver to break the clip.
The sensor is plugged in at the top behind the engine. When you are laying on your back and looking up the clips, you can see it. You’ll be drawn to the small plastic tab that you can see. This tab lifts up, but is actually used to remove the harness from the bracket! Here’s what I did:
- Climbed on top of the engine. - Carefully placed the 90 degree bent nose pliers on the clip and made sure it was the clip (you really can’t see). - While holding the pliers, snaked my other hand down and around (again, from the top of the engine) and pressed on the bottom plastic tab. - Once the tab was depressed fully, I put pressure in a DOWNWARDS motion (towards the floor) with the pliers. It popped right off!
After getting it removed from the bracket, the sensor is connected on the opposite side by another push tab. I made the mistake of pulling up on this tab and subsequently broke the little plastic piece. You want to press DOWN on this tab while separating the sensor. It should come away easily.
I then took the new sensor and loosely secured the three zip tie holders on the sleeve (so that way all I had to do was pop them in the bracket, tighten them down, and clip the excess).
Afterwards, I reconnected the sensor at the top and dropped the whole thing down the backside of the engine. From there, it was torquing it to spec (32 ft/lbs) and popping the zip tie clips back in. I left the 3rd one out just in case something comes up in the next few days.
At the top of the engine, I slid the sensor plug back onto the bracket (line it up and pull towards you). The bracket keeps it secure so even with my broken tab, it’s not going to separate.
Lastly, I disconnected my negative terminal on the battery for one minute to reset the “Check Emissions” notification.
I drove around for about 30 minutes and no lore “Check Emissions” light! Previously, it came on within ten minutes of driving after being reset.
Thanks for this thread, emry. It was my main source of info when taking this task on.
Here is what I put in my thread:
Success!
Here are the tools I used:
- 3/8 breaker bar - 3/8 torque wrench - 3/8 extension (about 5-6 inches) - O2 sensor socket remover (special socket, required) - Auto picks (get the longest reach you can find) - Long reach needle nose pliers AND long reach 90 degree bent nose pliers) - 18-inch flathead screwdriver - As many work lights as I could possibly find. - Headlamp - FYI the zip tie clips are part number 36538-RDM-A01 and they are super expensive. $11/each after shipping. No dealer in the country stocks them.
As emry had mentioned in his thread, the three zip tie clips are a PAIN. I got the first two off relatively quickly.
- The first zip clip is simple to remove. - The second is tricky. I was able to get it off with an auto pick that was “hooked”…not a 90 degree one. I wish mine was longer. But you want to get the plastic latch that you CANT see first. Once you get that one, you can press on the latch you can see and wiggle it free. - The third clip is my mortal enemy. Don’t even try to remove it. I had a pry bar, but it was too thick. So I used an 18-inch flathead screwdriver to break the clip.
The sensor is plugged in at the top behind the engine. When you are laying on your back and looking up the clips, you can see it. You’ll be drawn to the small plastic tab that you can see. This tab lifts up, but is actually used to remove the harness from the bracket! Here’s what I did:
- Climbed on top of the engine. - Carefully placed the 90 degree bent nose pliers on the clip and made sure it was the clip (you really can’t see). - While holding the pliers, snaked my other hand down and around (again, from the top of the engine) and pressed on the bottom plastic tab. - Once the tab was depressed fully, I put pressure in a DOWNWARDS motion (towards the floor) with the pliers. It popped right off!
After getting it removed from the bracket, the sensor is connected on the opposite side by another push tab. I made the mistake of pulling up on this tab and subsequently broke the little plastic piece. You want to press DOWN on this tab while separating the sensor. It should come away easily.
I then took the new sensor and loosely secured the three zip tie holders on the sleeve (so that way all I had to do was pop them in the bracket, tighten them down, and clip the excess).
Afterwards, I reconnected the sensor at the top and dropped the whole thing down the backside of the engine. From there, it was torquing it to spec (32 ft/lbs) and popping the zip tie clips back in. I left the 3rd one out just in case something comes up in the next few days.
At the top of the engine, I slid the sensor plug back onto the bracket (line it up and pull towards you). The bracket keeps it secure so even with my broken tab, it’s not going to separate.
Lastly, I disconnected my negative terminal on the battery for one minute to reset the “Check Emissions” notification.
I drove around for about 30 minutes and no lore “Check Emissions” light! Previously, it came on within ten minutes of driving after being reset.
Hope this helps someone!
thanks a lot for super detailed write up. By “the third” clip, were you referring to the one that’s the closest to the connector? And did you remove all three clips by working from underneath the vehicle?
thanks a lot for super detailed write up. By “the third” clip, were you referring to the one that’s the closest to the connector? And did you remove all three clips by working from underneath the vehicle?
thanks
Vick
Yup! Third clip in my write-up is the one closest to the connector. And they were all removed from underneath the vehicle.
