# Oxygen Sensors Replaced - Old vs New Pics



## CruzeEcoBlueTopaz (Jan 5, 2012)

I have replaced both oxygen sensors at 115k both worked properly and did not put out any error codes. I like to think my efficiency and performance increased slightly. For the past 10k miles I have noticed random 100 - 200rpm idle losses while in neutral and stopped that really only last a second and come with what feels like a small vibration on the peddles. So I did some research and a few possible causes were worn o2 sensors. I believe replacing the o2 sensors may have improved idle quality I will know for sure later today. 

I plan on replacing both sensors every 100k as preventative maintenance even though GM doesnt list specific intervals for them in the owners manual. 


As you can see the upstream sensor appears to be less worn which is the complete opposite I would excpect to see. I figure the downstream would be in better condition considering the exhaust has been in a sense filtered.


Upstream


Downstream


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## sciphi (Aug 26, 2011)

Let us know what you find. The old one looks to be in good shape. I'd keep it as a spare.


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## jblackburn (Apr 14, 2012)

O2 sensors are generally something that are a throw-away component, but it could serve as a backup in case you're stranded somewhere with an O2 sensor code and poor running. 

It always seems like my mass airflow sensors are the ones to take a dump though - I've been through 3 on other cars.

The only time I've had to replace an O2 sensor without a code, I noticed my gas mileage take a 6-8 MPG hit (this was on a car that went from 18 MPG city to 12 and 30 hwy to 22). Replaced the O2 sensor on a hunch after ruling out vacuum/boost leaks, and it was magically fixed!


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## CruzeEcoBlueTopaz (Jan 5, 2012)

So after replacing both oxygen sensors engine idle quality improved and is operating normally. Success !

As for my fuel efficiency well it has not been effected before or after replacing the sensors and is nominal.


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## iKermit (Dec 13, 2010)

http://www.cruzetalk.com/forum/98-mechanical/13831-replacing-oxygen-sensors.html

Per request, I have made a reference to this thread in the COMG-Mechanical section  Thanks CruzeEcoBlueTopaz for the information


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## Blue_RS (Aug 30, 2013)

How do you unplug the rear o2 sensor? I was under the car looking around for when i install the midpipe and couldnt see how it unplugs.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

There is a specific wrench for O2 sensors which makes removing both sensors that much easier.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

Replaced the oxygen sensors again today at 210k miles. This is a picture of the upstream oxygen sensor and had been used for 95k miles. The sensors appeared to be in good condition after 95k miles and in fact this oxygen sensor appeared to be in better condition then my original sensor that I replaced at 115k. Even though they werent putting out any codes I replaced them as part of my pro active maintenance plan. I read on a couple oxygen sensor manufacturer company websites that over time they do indeed become worn and less effective and that 100k is a good interval for replacing them.


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## Merc6 (Jun 8, 2013)

CruzeEcoBlueTopaz said:


> Replaced the oxygen sensors again today at 210k miles. This is a picture of the upstream oxygen sensor and had been used for 95k miles. The sensors appeared to be in good condition after 95k miles and in fact the picture makes it look less worn then it actually was. Even though they werent putting out any codes I replaced them as part of my pro active maintenance plan. I read on a couple oxygen sensor manufacturer company websites that over time they do indeed become worn and less effective and that 100k is a good interval for replacing them.


Yeah they don't send a code till they are good and dead, by then your MPG hit could have paid for the new sensors. I replaced up and down on my Buick to go from 19 mpg to 28 mpg. I did replace on on my Subaru but that was from a tuner giving me a super rich anti lag tune instead of the one I asked for. The Upstream should be cheaper than my $150 Subaru one.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

Well worth the $ 35 and $ 40 dollar cost to replace them both. I was able to maintain a 50.5 mpg actual average over the past week or about 1750 miles so I dont except much of an increase in mpg but who knows. Im happy to replace them knowing they are good for another 100k.


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## 2012CruzeEco (Sep 24, 2014)

Could someone post pictures of the locations of all the oxygen sensors? I have to replace the Bank 1 sensor pre-Cat, and I'm totally new to this process. This job seems relatively simple and I think while I'm down there I might replace all of them. Also curious to know which sensors need the O2 socket.

First time trying this, took it to my Chevy dealer whom I bought it from and they want to charge me $340 bucks, of which $97 in parts and $240 in labor. I'm not pleased, that seems like too much. I have a 2012 Cruze Eco (not diesel, 1.4L, 6 speed manual) with only 41,000 miles on it.


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## jblackburn (Apr 14, 2012)

2012CruzeEco said:


> Could someone post pictures of the locations of all the oxygen sensors? I have to replace the Bank 1 sensor pre-Cat, and I'm totally new to this process. This job seems relatively simple and I think while I'm down there I might replace all of them. Also curious to know which sensors need the O2 socket.
> 
> First time trying this, took it to my Chevy dealer whom I bought it from and they want to charge me $340 bucks, of which $97 in parts and $240 in labor. I'm not pleased, that seems like too much. I have a 2012 Cruze Eco (not diesel, 1.4L, 6 speed manual) with only 41,000 miles on it.


What code are you replacing it for? Most O2 sensor codes are actually caused by air metering or vacuum leaks (PCV valve cover making noise?)

If it truly is a bad O2 sensor, there is an emissions warranty that should cover this at that mileage.


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## 2012CruzeEco (Sep 24, 2014)

The codes from the diagnostics are P0132 and P0134. The car is still at the dealership, the service consultant said he's talked to the warranty office, the warranty was good until Sept. 4 2014 or 45,000 miles. Missed it by just a few weeks.


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## 2012CruzeEco (Sep 24, 2014)

By the way, thanks for such a quick reply!


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## jblackburn (Apr 14, 2012)

2012CruzeEco said:


> The codes from the diagnostics are P0132 and P0134. The car is still at the dealership, the service consultant said he's talked to the warranty office, the warranty was good until Sept. 4 2014 or 45,000 miles. Missed it by just a few weeks.


Ah ok...doesn't look like sensors fall under the emissions warranty either, which is only 20K/2 years on non-catalytic converter components. My mistake.

Yeah, unfortunately, those are codes that indicate the sensor itself died (high voltage & no activity, bank 1 sensor 1).

Bank 1, sensor 1, is the sensor right by the turbocharger up front (big blue wire).









Should be pretty easy to replace.


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## 2012CruzeEco (Sep 24, 2014)

No way, it's right there. Thank you for your help, I'll add to the thread letting you know how it turns out for me. Thank you again!


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## CruzeEcoBlueTopaz (Jan 5, 2012)

According to a couple different oxygen sensor manufacturer websites oxygen sensors do indeed degrade in performance slowly over time before they completely fail. I prefer to replace oxygen sensors every 100k as part of routine maintenance even though oxygen sensors have been prooven to properly function much longer. 

With that being said replacing the oxygen sensors is quite simple and im very surprised to see a dealer quote 2 1/2 hours labor for a 15 to 30 minute job depending on resources and how fast the person replacing the o2 sensors is willing to work. I find the most difficult part and to be honest its quite simple but disconnecting the o2 sensor wire harness can sometimes be a little hassle. Also to remove the 2nd sensor you might have to jack the cruze up and go at it from below unless your arms are long enough to reach the exhaust from above. 

Overall its a simple process.... update the post after your successful exchange.


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## 2012CruzeEco (Sep 24, 2014)

I got the car back from the dealership and they did not perform the repair, and you're absolutely correct, the O2 sensor wire harness is really a hassle. Mine seems stubbornly difficult to remove and I'm not sure how to disconnect it. Any advice would be greatly appreciated, I don't want to damage it.


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## CruzeEcoBlueTopaz (Jan 5, 2012)

So to remove the connectors pull the tabs on each side out as far as possible, once you do you will see it seperate itself, then all you have to do is firmly pull. Make sure you are pulling from both plastic connectors so you are not tugging on the wires. I dont recall but I dont think there are any spots on the connector that have to be pressed while pulling. It took me a couple attempts to remove it but eventually it came lose.


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## cruze2011white (Feb 2, 2011)

What size of socket does the oxygen sensor use to remove it? I can't find anywhere online what size it is.


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## jblackburn (Apr 14, 2012)

cruze2011white said:


> What size of socket does the oxygen sensor use to remove it? I can't find anywhere online what size it is.


Should be a standard O2 sensor wrench size - 7/8" I think. You can either get an offset wrench head or a socket that is cutaway to slip around the wire.


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## jsusanka (Jan 31, 2011)

remember when disconnecting sensors or headlights to spray some electronic cleaner on the electrical connection and a little dielectric grease on the connection. helps keep moisture from building on the connection.


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## pepel13 (Mar 20, 2015)

Might as well bring back this topic instead of creating a new one.

After getting these codes P0036/P0054/P0138/P140/P0141, all refering to Bank 2 Sensor 1, I wanted to changed it by myself thinking it would be a piece of cake. But since i'm not usually doing any mechanical stuff, that didn't go as planned lol.

Where am I supposed to find this sensor under the car? 

Doing a basic search before asking this but didn't find any precise information.

Any help will be very appreciated.

Thank-you


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## CruzeEcoBlueTopaz (Jan 5, 2012)

There are two sensors and they are both easy to find. The upstream sensor is located near the turbo and has a long blue connector its impossible to miss. The downstream sensor can be found simply by looking down behind the engine and you will notice a large sensor protruding from the exhaust pipe.The downstream sensor is identical to the upstream sensor in appearance except for a shorter black connector. The downstream sensor might require you to get under the engine to disconnect it.


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## carbon02 (Feb 25, 2011)

I had thought "Bank 2" referred to cars with two cylinder heads, and an oxygen sensor in each head's exhaust.

From reading engine theory for a previous GM engine. The first sensor is used for engine management, and the second sensor downstream typically measures the effectiveness or capacity to remove pollutants by the cat converter.

On the GM LX5 V6 engine, the codes set by the second sensor, were always capacity of the converter codes. These don't directly effect vehicle operation unless you're in a state where you have an emissions test.

Both sensors are relatively easy to access on the Cruze, but I'd be more tempted to change the one closest to the cylinder head first.


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## pepel13 (Mar 20, 2015)

Thanks for your reply.

I thought the sensor was located under the car, near the rear.

Did a quick look up and I found easily the blue sensor, but haven't seen the black one, which is the one I need to change).

I'll take a deeper look at the end of the day.

Thank-you.


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## pepel13 (Mar 20, 2015)

Finally found out that my o2 sensor was disconnected, how can it be possible?

My car still makes a silly noise under the hood while driving only. On idle everything is fine. 

Is it possible that since the o2 sensor was disconnected that ruined something in the engine? I didn't drive much with it since I had the check engine light on.


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## mikestony (Jan 17, 2013)

Sorry to resurrect an old thread, but I'm planning on doing some preventative 100,000+ mile maintenance by replacing both 02 sensors and ran across this on Alldata with regard to "HO2S heater resistance learn reset..."
I'm confused now. What happened to remove, replace and drive? 



> ALLDATA Repair - 2012 Chevrolet Cruze L4-1.4L Turbo - Heated Oxygen Sensor Resis. Page 1 of 1
> 2012 Chevrolet Cruze L4-1.4L Turbo Vehicle X Powertrain Management y Computers and Control Systems » Oxygen Sensor X Service Precautions X Heated Oxygen Sensor Resistance Learn Reset Caution
> Heated Oxygen Sensor Resistance Learn Reset Caution
> Caution: When replacing the HO2S perform the following:
> ...


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