DIY: Post-Cat O2 Sensors + Pre-Cat O2 Sensors

Originally Posted by jeepo23

So no issues retaping the hole to make the new 02 sensor go in nicely?

Cause I honestly have a feeling I am going to run into this issue lol..

I ripped tho theads out, there was no way to save them with how tight those sensors were. I had to make sure the tap was straight. New sensors went in fine. I put a good amount of anti-seize in it this time. If you can, get your hands on a good o2 sensor socket, not the $10 ones from autozone, those will just strip. Also see if you can get a buddy to help my brother-in-law is a mechanic so I used his help.

Originally Posted by phoopsta

I ripped tho theads out, there was no way to save them with how tight those sensors were. I had to make sure the tap was straight. New sensors went in fine. I put a good amount of anti-seize in it this time. If you can, get your hands on a good o2 sensor socket, not the $10 ones from autozone, those will just strip. Also see if you can get a buddy to help my brother-in-law is a mechanic so I used his help.

Alright, quick question.. if you destroyed the threads and ripped them out. How were you able to get the thread retapped the same size to fit the new sensor?

Or am I missing something here? Know what I mean?

Originally Posted by jeepo23

Alright, quick question.. if you destroyed the threads and ripped them out. How were you able to get the thread retapped the same size to fit the new sensor?

Or am I missing something here? Know what I mean?

I used a tap I dont remember the size on the top of my head. 18x1.5? Not sure.

Well I just swapped this O2 sensor, what a bastard. I used a acetylene torch, along with a can of Freeze Out.

Finally it came out but the threads were somewhat destroyed. I managed to screw the new one in as far as it would go - good enough I think.

The light is still on, how long before that light shuts itself off? I am not at home so I didn't have access to my computer to reset the light that way. Could the light be staying on due to this cross threading thing now? I've only driven about 10km with the new sensor installed.


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Originally Posted by jeepo23

Well I just swapped this O2 sensor, what a bastard. I used a acetylene torch, along with a can of Freeze Out.

Finally it came out but the threads were somewhat destroyed. I managed to screw the new one in as far as it would go - good enough I think.

The light is still on, how long before that light shuts itself off? I am not at home so I didn't have access to my computer to reset the light that way. Could the light be staying on due to this cross threading thing now? I've only driven about 10km with the new sensor installed.

IF the problem has cleared by replacing the O2 sensors, it will take between 20-40 start cycles for the light and codes to clear by themselves.

Originally Posted by jfoj

IF the problem has cleared by replacing the O2 sensors, it will take between 20-40 start cycles for the light and codes to clear by themselves.

Wicked, thanks man yah I figured I haven't given the car enough drive cycles to clear on their own. Tmr when I return home I can also reset it using my scanner and see if it stays off or comes back on - I've had this light on for way too long so I'm quite excited to get it to turn off


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197K kms (122k miles) and started getting lean code and heater code on bank 2. Changed out both pre-cat sensors and now no codes. Thanks for the info. I tried to use a sensor socket, but it wasn't long enough for our sensors so had to use the crows foot wrench to do it.

I cleared my codes using the Torque app.

My 323 has 112,00 Just did my post-cats. I have not done my fronts. My mechanics says that most O2 sensors fail around 100K but some last much longer so it is best to wait for the SES light and codes to tell you they are bad and then just replace the bad ones. The pics on this thread are great. I used a short O2 crowsfoot socket and a 3/8 ratchet with a joint (pic) to get the one that sticks straight up. I used the deep O2 socket (pic) and a 3/8 ratchet for the one at an angle. To thread them through, I just cleaned off the exhaust end of the old sensor and taped the plug end of the new one to it. Then I had someone carefully pull the old one up from on top. I also found that I only needed to jack up the front driver's side of the car to get good clearance.
https://dailyegypt.net/

Have any of your guys done this on an E46 with a ZF 5HP19 transmission, if so what is the clearance like for the post-cat O2 sensors?

Just did this. I did not remove the reinforcement plate. Removed the front sensor with a 22mm open end wrench. The back one was trickier, bur I got it with a crows foot socket, a 3" extension and a breaker bar. Took about 15 minutes to remove both.

Much longer to thread the wires

Does someone know for sure which connection for the post cats on top goes to which bank. I might have mixed mine up.

Or, the O2 sensor that was more visible and easier to remove goes to the plug socket closer to the oil filter.

Just a quick FYI , I am sure this is all been in mind of this thread or at least in mind of those who read, but the steps here are for pre 2003 models that have 4 wire sensors, (the older E46s) the newer late 2003 and up cars have 6 wire sensors, that have different plugs, functions, MS 45 ECU and there is more to it. Again just FYI.

I got what I was looking for, thanks