Pre-Cat O2 sensor change pics

Brian_Fantana · 06-20-2015, 06:15 PM

Ok this wasn't hard but definitely not fun or easy. Total time was about 1.5 hours. I put my car up on some cheap ramps from harbor freight which gave me about 4" of clearance from my chest.

My advice:

Don't waste your time trying to work around removing the transmission cover (6 screws) the skid plate (10 screws) or the passenger side sensor shield (2 screws).

The driver side is a cake walk and only required the transmission cover off to access the sensors electrical mount.

Passenger side has a shield that will require you to remove everything else to access the mount the electrical plugin sits in.

I'm not sure how bad these look but the carbon build up looks somewhat bad. I only turned over the engine to verify I wasn't throwing any codes.

I will drive it later to see if I can feel a difference.

Brian_Fantana · 06-20-2015, 06:18 PM

Here are the pics

Brian_Fantana · 06-20-2015, 06:23 PM

And some others

O2 sensor conditions
http://m.walkerproducts.com/o2-sensors/#conditions

jdamore · 06-23-2015, 10:48 AM

How is she running with the new plugs and O2 sensors?

jdamore · 06-23-2015, 11:00 AM

For you Brian Fantana..

Brian_Fantana · 06-23-2015, 06:10 PM

Quote:

Originally Posted by jdamore

For you Brian Fantana..

Haha! Love that.

She is running fantastic. I'm noticing a huge difference in low RPM power. She just seems much more eager to run. I'm not sure if it was the plugs or the O2 sensors because I didn't drive it until they were both done, but wow. It may be in my head but my butt dyno lies to no man. Especially not me

You can see from the link I posted it seems like my engine seems to be running on the rich side as well. Perhaps this fixed or helped that? IDK but well worth the time it required.

ONE_slow_m5 · 11-11-2015, 10:41 AM

Quote:

Originally Posted by Brian_Fantana

Haha! Love that.

She is running fantastic. I'm noticing a huge difference in low RPM power. She just seems much more eager to run. I'm not sure if it was the plugs or the O2 sensors because I didn't drive it until they were both done, but wow. It may be in my head but my butt dyno lies to no man. Especially not me

You can see from the link I posted it seems like my engine seems to be running on the rich side as well. Perhaps this fixed or helped that? IDK but well worth the time it required.

any pics where these sit ?

atruelunatic · 11-11-2015, 05:57 PM

Adding to the previous question, do you have the size wrench and torque values for the sensors?

Brian_Fantana · 11-18-2015, 01:54 PM

Quote:

Originally Posted by atruelunatic

Adding to the previous question, do you have the size wrench and torque values for the sensors?

Sorry I don't remember now. I want to say 15mm open head wrench but I can't remember.

ONE_slow_m5 · 11-18-2015, 08:02 PM

Quote:

Originally Posted by atruelunatic

Adding to the previous question, do you have the size wrench and torque values for the sensors?

7/8th will do

Theodore · 09-27-2016, 01:09 AM

Quote:

Originally Posted by Brian_Fantana

Sorry I don't remember now. I want to say 15mm open head wrench but I can't remember.

Thanks for the write up! For those tackling this job, these pre-cat O2 sensors require a 22 mm open-end wrench (7/8 inch is nearly the same size). Unfortunately the electrical plug end of the sensor is too large to fit through a ratcheting box-end wrench and there is not enough space to successfully use an O2 sensor socket, so you are stuck using an open-end wrench on this job.

To make removal of the old sensors a little easier:
A. Try to do this job while the exhaust is still warm (but not "burn yourself" hot)
B. Spray some Liquid Wrench on there to soak in the threads for a good 20+ minutes before removal
C. Help break the corrosion by slightly tightening the sensor onto the exhaust (maybe a 5 degree turn) before trying to loosen the sensor off the exhaust.

Here is a picture of my unsuccessful attempt to use an O2 sensor socket.

TWiTCHY · 11-17-2016, 11:45 PM

Quote:

Originally Posted by Theodore

C. Help break the corrosion by slightly tightening the sensor onto the exhaust (maybe a 5 degree turn) before trying to loosen the sensor off the exhaust.

I've been told to use a thread chaser after removal, but can anyone attest to skipping that step or performing Theodore's tip?

JsL · 11-17-2016, 11:56 PM

Can you take a pic of where to press on the connector to disconnect the sensor from the harness?

111turbo · 12-12-2016, 05:47 PM

Great advice! I just got my precat sensor changed also and car seems to run a bit smoother.

06-20-2015, 06:15 PM	#1
Brian_Fantana Second Lieutenant 84 Rep 225 Posts Drives: 09 Alpine white E90 M3 DCT Join Date: May 2013 Location: Gig harbor wa iTrader: (0) Garage List 2009 M3 [0.00]	Pre-Cat O2 sensor change pics Ok this wasn't hard but definitely not fun or easy. Total time was about 1.5 hours. I put my car up on some cheap ramps from harbor freight which gave me about 4" of clearance from my chest. My advice: Don't waste your time trying to work around removing the transmission cover (6 screws) the skid plate (10 screws) or the passenger side sensor shield (2 screws). The driver side is a cake walk and only required the transmission cover off to access the sensors electrical mount. Passenger side has a shield that will require you to remove everything else to access the mount the electrical plugin sits in. I'm not sure how bad these look but the carbon build up looks somewhat bad. I only turned over the engine to verify I wasn't throwing any codes. I will drive it later to see if I can feel a difference. __________________ They've done studies, you know. Sixty percent of the time, it works every time. ~ Brian Fantana
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06-20-2015, 06:18 PM	#2
Brian_Fantana Second Lieutenant 84 Rep 225 Posts Drives: 09 Alpine white E90 M3 DCT Join Date: May 2013 Location: Gig harbor wa iTrader: (0) Garage List 2009 M3 [0.00]	Here are the pics Attached Images __________________ They've done studies, you know. Sixty percent of the time, it works every time. ~ Brian Fantana
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06-20-2015, 06:23 PM	#3
Brian_Fantana Second Lieutenant 84 Rep 225 Posts Drives: 09 Alpine white E90 M3 DCT Join Date: May 2013 Location: Gig harbor wa iTrader: (0) Garage List 2009 M3 [0.00]	And some others O2 sensor conditions http://m.walkerproducts.com/o2-sensors/#conditions Attached Images __________________ They've done studies, you know. Sixty percent of the time, it works every time. ~ Brian Fantana
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06-23-2015, 10:48 AM	#4
jdamore Captain 433 Rep 855 Posts Drives: 2008 e92 M3 Join Date: May 2013 Location: New Jersey iTrader: (4)	How is she running with the new plugs and O2 sensors? __________________ -- 08 JB e92 6MT ///M3 ESS VT2-625 --
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06-23-2015, 11:00 AM	#5
jdamore Captain 433 Rep 855 Posts Drives: 2008 e92 M3 Join Date: May 2013 Location: New Jersey iTrader: (4)	For you Brian Fantana.. Attached Images __________________ -- 08 JB e92 6MT ///M3 ESS VT2-625 --
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11-11-2015, 05:57 PM	#8
atruelunatic Lieutenant 96 Rep 473 Posts Drives: n/a Join Date: Jun 2011 Location: Seattle, WA iTrader: (1)	Adding to the previous question, do you have the size wrench and torque values for the sensors? __________________ 2011 e92 JzB 6MT Akrapovic Evolution, ESS Tune, KW V3
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11-17-2016, 11:56 PM	#13
JsL Major 448 Rep 1,263 Posts Drives: 2011 AW M3 ZCP Join Date: Dec 2013 Location: SF Bay Area iTrader: (2)	Can you take a pic of where to press on the connector to disconnect the sensor from the harness?
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12-12-2016, 05:47 PM	#14
111turbo Private First Class 81 Rep 130 Posts Drives: '12 e92 M3 Join Date: Jan 2015 Location: NY iTrader: (1)	Great advice! I just got my precat sensor changed also and car seems to run a bit smoother.
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