Quick tips for pre-cat O2 sensor change?

[JeffPortland]

I can't find any DYI info on this. Hopefully that means it's straight forward:
M-Roadster-O2-sensor.JPG
S52 99 M Roadster:
I just reset the code... this is the second time I did this so I know it's coming back. I already bought the NTK OEM-identical sensors. I am going to go use a friend's garage to do the work and want to show up ready. I have the open ended o2 sensor socket, anti-seize, dielectric grease (for the plug seal), I am planning to clean out the connectors on the car side with Deoxit... My concern is getting the car up and not being able to reach the sensors. How necessary is having some penetrating oil handy? Will I need to remove anything to reach the sensors on the headers?

I bought two of these for pre-cat:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Thanks!

[bluptgm3]

Pretty straight forward. Pull the passenger side wheel and lift car enough to work.
I’ve not used anti-seize on O2 sensors and I’ve done and redone a few.
Remove the valve cover beauty cover to access the connectors.
There is a slot in the back of the valve cover that the wires are routed in, in addition to a sheet metal ‘hook’ on the firewall and frame rail.
The aft bank O2 sensor attaches to forward connector under the beauty cover and forward bank O2 attaches to aft connector.
Don’t mix these up, you will have a run issue and get codes…ask me how I know.

I use an open end wrench with good success.
Detach the connectors first and drop the wires in to the head pipes to remove the sensors, reverse for installation.
Should take less than an hour the first time doing them.

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[Schreier]

I haven't changed many O2 sensors, but when I have, they typically come with anti-seize paste already applied to the threads. Inspect the new O2 sensors to make sure.

[JeffPortland]

Pretty straight forward....

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I really appreciate this. Thank you!

[JeffPortland]

So the light came on just after hitting a bump on the highway. I've cleared it a couple times and it always kicks on around 3100 RPM. I started thinking... the frequency of vibration at 3100 rpm and the association with a bump in the road... Could it just be the electrical contact?? I sprayed the o2 sensor contacts with Deoxit and seated the connector on and off a few times. Code hasn't returned. I'll let you know if it does.

[JeffPortland]

So the light came on just after hitting a bump on the highway. I've cleared it a couple times and it always kicks on around 3100 RPM. I started thinking... the frequency of vibration at 3100 rpm and the association with a bump in the road... Could it just be the electrical contact?? I sprayed the o2 sensor contacts with Deoxit and seated the connector on and off a few times. Code hasn't returned. I'll let you know if it does.

Cleaning oxidation from the contacts appears to have fixed my O2 sensor code (18 days later, daily driving 1.5 hours/day). Literally took 5 minutes and barely got my hands dirty. Saving my new sensors for when the old sensors actually go bad...

[JeffPortland]

Cleaning oxidation from the contacts appears to have fixed my O2 sensor code (18 days later, daily driving 1.5 hours/day). Literally took 5 minutes and barely got my hands dirty. Saving my new sensors for when the old sensors actually go bad...

Sensor light came back on... Decided to just change the sensors. Before starting this project I could not find photos of the O2 sensor locations or plug locations. I was able to figure it out just fine and took me about 2 hours. I could do it again much much faster.

So here are some photos. Pardon the PB blaster on the sensors:

Sensors are on the headers (passenger side) visible below the car:

S52-Pre-Cat-O2-Sensors.jpg S52-Precat-O2-Sensor-1.jpg

From the sensors there are metal clips that hold the wires and route them around the rear of the engine. There are a couple for the zone 1 sensor only. The zone 2 sensor wire joins for the last ~2 clips as they route up the back of the engine. the last 3 clips reachable from the top of the engine are plastic:

Zone1 wire clips.jpg Zone1&2 clip buttom side.jpg PlasticWireClips-top-side.jpg

[JeffPortland]

To do the job you need to remove both of the plastic covers on top of the engine. The sensors plug in on top of the engine.

Attachment 663432 Attachment 663433