My '03 MCS with 122k miles has the original O2 sensors, and Mini suggests they be replaced at 100k miles. Should I just wait until they fail, or is it going to happen soon anyway? Is this a DIY job? I'm reasonably handy, but I've never replaced an O2 sensor on any car or truck before. I've read through a lot of other posts, and I can see that I'm going to need to purchase an O2 sensor socket (are they all the same size, 22mm or 7/8 in?) and that several people recommended getting sensors that are exact OE fits, versus universal fit units that will require cutting wires. Anything else I need to know? How difficult is it to get the original sensors out, or is it not that bad because (hopefully) they used an anti seize compound on the threads at the factory? Do I really need the special torque wrench that Bentley shows in the their service manual? (I've got a pretty good idea what 29 ft. lbs. feels like, is the EXACT tightness critical?) If the dashboard service light has never been on due to a sensor problem, is there anything that will need to be re-set in the engine computer? Thanks in advance for your help.

 

Well...., I can tell you that getting my pre-cat o2 sensor out was a snap using the special socket sold thru Bavarian Autosport. I don't know why anybody would want to get a sensor that isn't a direct replacement - negating splicing wires. It did require some thread locker because of the high temps when replaced..

 

We find that the easiest way to replace them is using a 22mm open end wrench. We have them in stock if you need em.
http://www.waymotorworks.com/product...1&cat=0&page=1

 

Don't change them until they fail--either they work or they don't, and when they fail, you'll get a check engine light. Treat your O2 sensors like NASCARs: Run 'em sombitches til they blow up.

 

 

Helix is right on. There are two O 2 sensors, one up on the exhaust manifold, the other just after the catalytic converter.
Don't mess with them until the dashboard light tells you.
These guys can easily last 250,000 miles without replacing.
Just another dealer way to cost you alittle more with service.

 

204,000 miles on the original sensors. I'll wait until they fail, then replace.

Jim

 

If it ain't broke...don't fix it.

 

So I've had my dash light come on a couple times. Took it to my local shop as I am past warranty (83k) and dealer is 70 miles away.

First time, diagnosis was engine was running too lean. They adjusted the computer settings, and I was off and running.

Second time in, diagnosis was O2 sensors "dirty", may need replacing. They were able to get clear the light on the dash and a week later light came on again.

I'd like to be able to do this myself. Sounds like it's fairly straight forward. I've changed the oil in her a couple of times now. Is this something that the right parts and instruments will solve for me?

 

If the problem is a bad O2 sensor....replacing will correct the problem...if the sensor is working fine, and the car is running lean, or you have an air leak...the o2 sensor will not fix it.
Most folks run 02 sensors until the computer determines it is not working....but they can get "lazy" or slow to respond with age....but if you are not experiencing any symptoms, the fraction of a MPG you will get with a new o2 sensor will never be worth it IMO.
Funny how a dealer called a sensor "dirty". Generally they are not considered a serviceable unit...if there is lots of soot, it could be wiped off, very gently, but this is kinda something a dealer is unlikely to do.
One thing...many gen1 MINI's have a 10 yr, 100,000 warranty on the o2 sensor...they were failing too fast, so mini gave them a separate warranty...I think some 04's and 05's got the warranty...call the dealer with your vin to be sure....

 

Thanks for the info ZippyNH. The shop I took it to is NOT a dealer as mentined before, closest dealer is 70 miles away. So, yes, I think they "cleaned" off the dirty O2 sensor. And I think they opined that the O2 sensors are going bad and would need replacing if the light came on again like it has.

I'm not worried about better gas mileage. I just hate the Service Engine Light staring at me in the face all day and night.

 

So, does anyone have a How To posted. Would love to see a tutorial (ala fuel filter; oil change; sparkies) so I can do this myself. My two NTKs are on their way. MINI will do it for $69 (very reasonable IMO) but still would like to take a crack at it my own self. Anybody???

 

Here's a DIY:
Take 22mm wrench and remove, then install new ones and tighten with 22mm wrench.

 

I had my post-cat go at 39k miles on my '02.

 

You're a vendor? I understood that a 22mm socket would be required. Was seeking more in the way of a real DIY, as in where stuff is. Potential pitfalls... Etc. You have helped me a great deal ... NOT.

 

There is no special tips or tricks it's VERY straight forward. And NO you don't need a socket, I use a 22mm wrench everytime I change one.

 

A socket won't work unless you have an Oxygen sensor socket with the cutout for the wires to go through. The wrench will allow the wires to not be messed with while taking the sensor off.

Pitfalls, spray with a penetrating oil as a part that is under the car and on the hot exhaust will have some corrosion and tons of heat cycles, further tightening the threads together. Look for the sensors, spray with penetrating oil, and wrench off. Not too terribly difficult.

 

Yeah, guess don't need the specialty sensor wrench with the slot. ...

Just disconnect the electronic end, run the 22mm box end wrench up along the wire to the sensor, tighten sensor, torque a bit, remove wrench down the wire. Connect electronic end. Do for other sensor. Done.

Only thing is I don't know where any of the connections are, so don't know about clearance nor what space I'm working in... Is there enough clearance for tightening both sensors with the regular wrench on the "spark plug" end?

Pictures anyone? The pics for a fuel filter swap were the only thing that kept me from totally fu##ing up...

Just need some pics, that's all. Thanks!

 

MJL,
I just replaced mine-it's fairly easy. I put the car on ramps. I used the special socket tool (bought on ebay), but I can see how a regular open wrench would have worked fine. I followed the white jacket wire down to the (manifold) sensor, and unscrewed the old one. Then I ran the new one along the same path while the old one was still in place so I knew it was run correctly. I connected the new one to the harness after screwing it in so the wires wouldn't twist up when cranking it down. I wish I had taken time to tape the ends of the jacket-it's loose and the wires are easily exposed f you pull on the jacket. Now, is there a way to reset the code I wonder?

 

Well, I chickened out of doing my oxygen sensors, opting to go to a MINI shop, which charged me what I think was a very reasonable price for installation: $69 (my cost for the OEM NGK sensors was $200 for 2). Had everything prepared and got under the car, only to realize that if I started and ran into trouble (seized sensor, etc.), I'd be sunk as the maximum I'll stay under a car is 15-20 minutes... Anyway, fast forward. The two sensors were installed today... I distinctly remember one poster having said that he connected the plug end first then screwed in the sensor side; that way, he indicated he'd avoid turning the wires. In other words, the plug end should be disconnected when you're wrenching the sensor into the exhaust. Well, don't you know... I looked at one of the sensors (viewable via the front end) and there was the sensor, with the four wires trailing it turned around. Now, I also remember reading one is not to "kink" the cable. That strikes me as more of an issue of severely bending the cable. Is what I've described with my install detrimental to the sensor? In other words, could the mechanic's technique have rendered the sensor and its function problematic? Thanks!

Question 2: I have personally installed new plugs/wires, fuel pump, poured Seafom into the fuel, changed gas, cleaned and made sure connections of the battery terminals were sound, and now had the O2 sensors installed, etc. in an attempt to stop the following "symptom" and I've yet to eliminate it. ... Upon starting, the engine will rev to 1,000 RPM or whatever starting point, then suddenly cycle down (as if the engine is losing power), then ramp up again. There is no stall or anything. I was thinking it might be the ignition coil, having read a post on that. But after all of these expenses I've incurred, I'd rather hear from someone before I take on another project/expense.

Your input is greatly appreciated on the above questions.

 

I have a 2002 MCS with a P0136 code registering that I have reset (using my OBDII reader) for the O2 sensor. It kicks on each time I go into high rpms. I'm curious about the 100,000 ten year warranty on O2 sensors. Where did you hear about this? I'm interested since I'm taking my '02 into the dealer tomorrow and I'd love it if somehow it were covered under a warranty.

 

2002 MINI's didn't get the 10yr/100k mile oxygen warranty. That extension was given to the 05-06 MINI's that had the problems with them.

 

My SES light came on last week, took it to my shop yesterday, bad 02 sensors. '05 R53, 99k miles. Called the dealership, they said if it is the sensors they will replace them for free. I scheduled my appointment for next week.

 

Damnit i just replaced my 02 sensors on my 05 S .. never knew about the warranty >.<

 

I am currently doing this in my driveway but oddly enough, the sensors coming out of the threads was not my problem. its the electronic end that i cant get loose. i press down the little plastic piece and its supposed to just slide out, right? cant seem to get it to budge. the one located under the hood i pressed the plastic piece down too hard i suppose cause it snapped right in half :| i'm frustrated with this.