Hello, new to this site and this is my first post.

I have a 2004 RX-8 6 speed manual. Love the car, but about a month ago it started running like crap - real sluggish off the line and harder to shift than usual. So I took it to one of the Auto Parts places and had them hook it up to their diagnostic machine. O2 sensor failure. Took it to the guys that usually work on all my vehicles for confirmation and they said it's a bad Heated Upper O2 Sensor.

Here's the part I'm having trouble with: He says he can't order the part except through Mazda and it'll cost $304, plus $60 labor, plus tax for a total of $388. If I find the part somewhere cheaper - they will install it for $60, but not guarantee the fit/operation.

I call the Mazda dealership who scares me into making an appointment by saying, "Well it MIGHT not be that issue, it might be something else becasue XYZ Auto Guys dont have a Mazda certified diagnostic machine" and if you bring it to us, we can make sure that the O2 sensor is the real issue and guarantee the work". Their cost - $389 (amazing, right?) - plus the diagnostic fee of $95. But the dealership is a lot farther away than XYZ, and as bad as my gas mileage is at this point, I would prefer to have it worked on by the local guy for the same price, if I get the same effect.

So I look online, and I see $17, $33, $25 O2 sensors all over the place. Obviously, I need the "Heated Before Catalytic" one and found: WALKER PRODUCTS OXYGEN SENSOR, 4 WIRE, BEFORE CATALYTIC CONVERTER -- A Direct Fit Replacement Part, Designed To Improve Engine Response, Gas Mileage, And Lower Emissions, Exceeds OEM Specifications And Test Requirements, Original Equipment Part Number N3H218861C" for $127.00.

Last resort, I call Advanced Auto, who says they have a universal one that they guarantee will fit my car, but the wire have to be spliced to make it work. That's only $70. As opposed to the $33 "Universal Fit" online. What's the difference?

What do I do? What the hell is the difference between all of these things and why is there such a drastic price discrepancy between what XYZ and Mazda can get versus what I can order online? I feel like I'm geting the run around from these repair shops and from the dealer because I'm a girl who doesnt know a lot about engines. In these economic times, I'd much prefer to spend as little as possible, but I also want to make sure I'm not putting sub-standard parts in my car that may cause other issues.

Any ideas from those that have been there? Thanks.

 

first off, welcome SuperG!

I used the Search Feature towards the top right (advanced search, search thread titles only) and found the following threads:

https://www.rx8club.com/showthread.p...ight=02+sensor

checking a few sites now, let me see what I can find.
www.onlinemazdaparts.com has the 02 sensors, just enter your year and then pick Automatic or Manual Transmission.


As for taking it to Mazda, I don't see the need since your mechanic probably used an OBD II reader to pull the code which is similar to what Mazda is going ot use. Save yourself the money and use it towards a new OEM 02 sensor.
Also, replacing an 02 sensor is super easy, I wouldn't pay a guy $60 to do it.

 

Thanks for the welcome Jedi54. I read that thread you cited eariler, but I'm still a little confused about the pricing differences. I also looked on the onlinemadaparts website and swa the sensor for $243. From what I have researched, it appears that the Walker part is the least expensive (of the expensives), but not sure if that one is a suitable replacement.

 

I replaced my lower 02 sensor about a month ago. I bought the part from onlinemazdaparts from the above link. Bought a bigger adjustable wrench cause i didn't have a wrench big enough. 5 minutes, a little bit of elbow grease and i was done. There is probably a pic somewhere on here of the upper o2 sensor and you can do it yourself. Save yourself about 200 bucks.

I wouldn't buy one of those $30 ones considering the o2 sensors get more complicated every year and if it doesn't work properly your gas mileage will really suck.

the cheaper ones don't check your oxygen levels as quickly as the mazda ones, they aren't heated, and they don't have the electric plug designed to plug directly into the wiring. the reason its so expesnive is because its heated, the lower one is about $100 less because of that i believe.

found this on another thread on the price difference:

"he front one is a wideband and the rear one is not--make sure you get a true wideband sensor for the front."

 

get it from onlinemazdaparts and install it urself ... it might be hard cuz after all the heat expand/cool off shrink. it might be tight, get the right size socket and u're good to go.

243 + 6 bux shipping and no tax if u're not in their state, socket cost less than 10 bux. 1 hour of ur time. u're good to go.

 

Meh, $60 isn't bad if you don't have the first clue about what you're doing and don't own any tools. But like everybody else said, this really isn't hard to do.

Definitely get an OEM front O2 sensor. It is responsible for controlling your car's fuel trims, and it is important that the responsiveness and signal are what the PCM expects.

Maybe I'm crazy, but the front O2 sensor for our car costs $304.85 from http://www.onlinemazdaparts.com?


EDIT: Also, has your mechanic verified the integrity of the connector and wiring harness? It's possible that the sensor itself is fine.

 

naw, it cost 230 something @ onlinemazdaparts.com he said 304 cuz thats what his dealership told him

Mine never gave me any problems, but I still replaced it about 3K miles ago. that time I was doing my clutch so might as well replace it at the same time.

 

FYI- I have a used sensor that has 300+ miles on it. Let me know if you want it asking $150.00 plus shipping which should be fairly cheap.

 

I believe the two sensors are different. One is expensive.

Also many get the treads stripped when removed.

You had better be prepared for that.

 

Front cost 230+, Rear one cost like 120 or 130 I think.

reason ? front is wideband, need it for O2 feedback to ECU. The Rear one is there just to check Cat's efficiency

 

Thank you all so much for your help, I really appreciate it. As I have no clue regarding the workings of engines, and I have no tools, I think my best bet is to suck it up, order the part from onlinemazdaparts for $243 and try to solicit one of my car-savy friends to help me. Hopefully, I can learn some things in the process so I'm not so helpless in the future. Thanks again.

 

with your o2 sensors you really need to get the factory one not a universal mazda made it for the car and the way the rotory runs it needs the be accurate i would go factory for bank 1 sensor 1 but u could go after market with bank 1 sensor two( the o2 sensor after the cat) because all it dose if it is failed is turn on ur check engine light not go in limp mode because all it dose is measures ur cat efficant and not back rather then tell your ecu its fuel ratio

 

didn't I said the same thing in #10 ...

 

So, and I apologize for reiterating the obvious (but like I said before, I am enigne oblivious) - but I should just keep my appointment with Mazda and let them install it for a total of $400 instead of buying the one for $243 on-line and having a friend install it? The one on the site (or the $127 Walker) won't work?: http://www.trademotion.com/partlocator/index.cfm?action=getJointLocator&siteid=214264[/url]

Thanks again

 

IMHO, you should let the dealer install it. $60 isn't bad - it's a bit more than half an hour at typical dealer rates. Save $60 by ordering it yourself. That dealer seems like a good guy for a) quoting a fraction of an hour rather than a whole hour, and b) letting you get the part yourself and not jacking up the labor.

Ken

 

its very easy to install the plug if u have access to a lift.

if u're installing it at ur garage, pumpin' the jack + put on jackstand takes maybe another 10-15 minutes.

that is if u have the right O2 sensor socket tho.

prepare to spray tons of wd40 around that area.

 

Has anyone actually used one of the Walker O2 sensors for pre cat on an MT?

 

alright someone PLEASE sum this up in as little as possible so that EVEN i understand

 

^Unless you really know what you're doing and want to be a guinea pig, get the OE front O2 sensor.

 

i have 2 guinea pigs

 

this **** is so much harder tahn the rear sensor to change. theres no room with all the heat shields , i must be missing the easy part

 

So I'm getting the fix me light, obd code says something like catalitic efficency below threshold (bank one), and my already low gas mileage has plunged far below acceptable levels on my 05 mt... My broke @$$ is dreading buying a $200 + sensor... Are there really no alternatves? Why does the o2 sensor need to be heated anyway? Seems like the hot gasses already coming out would do a pretty good job of heating that thing up with the quickness

 

04 Rx8. 6 MT. No Cat Converter. Auto Exe Exhaust. Mileage 10K miles.
(new plugs)

BHR Ignition Coils: CEL code P0351 to P0354 (for the after market coils as expected).
Drove about 600 Miles with the CEL on. CEL code P0031 (came on and off at times)
Problem: Ignition Cut off at around 6500 rpm (2nd gear)

Mechanic said the coil wires are not messed up.
Changed back to the stock coils: CEL P0031 (front O2 sensor)
Drives sort of ok. Felt the ignition cut off at around 7500 rmp at one of the pulls (2nd gear)

Fuel consumption is high for sure.. idle is ok..

Can the front O2 sensor be a reason for the ignition cut off?
The mechanic wasnt too convincing when he mentioned that the BHR coil wires were messed up. Are the coils &wires ok?

Any suggestions would be appreciated.

 

Adding details P0031: HO2S11 circuit out of range low voltage.

 

Thanks for using the search...but replying to a thread that is a year and a half old that contains the answers is not really cool.

Yes...a CEL for a failing/failed O2 sensor or Cat can cause your car to run like crap and kill your gas mileage. Pretty sure your code is for the rear O2 sensor so replace it and be done.