Autozone says "....O2 Sensor Malfunction bank 1 sensor 2..." @ 42800 miles.

Anyone else foul a plug yet? I think v36 did it....

 

O2 sensor malfunction isn't fouling a plug - most likely a "malfunctioning O2 sensor". There are two on the car, one before the cat, and one after. I don't know which one this refers to, but I would take a SWAG and say the one after the cat (sensor 2).

What was the specific DTC code? I can look it up in the MINI-specific listing and see if it matches AutoZone's definition. Sometimes the same DTC code means different things depending upon the manufacturer --

 

Foul/malufunction, same thing... bad plug.

Specific code read similar to above. I don't recall a "code number" type thing... the reader just scrolled something to the likes of the above. Maybe "Emission control malfunction bank 1 sensor 2..."

Which brings me to another question: Replacement bmw part number/ product code (as in NGK, Denso, etc)? I know, according to warranty and phone call, emissions control warranty covers at least 4yr/50k, but good to know the part numbers anyway.

 

Bank1 sensor 2 is the rear sensor. This one doesn't normal fail before the first, since it is further downstream and has the cat to clean up some of the garbage. Good luck with it.

 

I had the same problem... My dealer checked and told me it was the O2 sensor just after the catalyst converter. It will be changed next week under warranty.

Hope this help!

P.S: I'm running on ECU Version 37 so I really don't think your ECU has something to do with it!

 

Goin440, did you understand that this is not a sparkplug problem, but an oxygen sensor problem?

And really, it's probably just that the wire fell off or got corroded.

Get under the car and check the wires to the oxygen sensor screwed into the exhaust pipe after the catalytic converter.

 

... something far more expensive. I had the "Service Engine Soon" light come on a couple of times, finally staying on long enough for a trip to the dealership. Lee, the highly competent tech at Century MINI in Greenville, SC, said that there were several possible causes and started with the cheapest: he replaced the oxygen sensor, first in the before-the-cat position, then in the after-cat position and neither solved the problem.

A new DME (engine control computer) was installed, which did solve the problem. Fortunately, the car was still under warranty (15,000 miles): the box retails for more than $1,100.

I'd not noticed any serious degradation of the car's performance, but it certainly got better gas mileage after the replacement. I’m now getting close to 30 mpg, despite living in the mountains of western NC and driving like I enjoy it.

 

goin440,

We need to know the exact code in order to help you. There are several codes that relate to the O2 sensor. If it is the slow warm up code, you can just reset the code and it will probably go quite a while before setting again. As previous posters indicated, it is highly unlikely that there is ANY relation with this code and spark plugs. If it is another O2 code it could mean other things. Let us know the exact code and we can help further.

Again as indicated by an earlier poster, check the wiring to the sensor.

LJinNC,

It sounds as if the cause of your Service Engine light has nothing to do with goin440's. When the light illuminates it is simply notifying you that there is a problem. The exact nature of the problem could be a myriad of things. Once you get the code, then you narrow it down further. Even if the light comes on and then goes off, the error code is still present and can be read to determine the exact nature of the problem.

Good luck to all.

 

My “Service Engine Soon” light came on, then went off. On the first trip to the dealership the tech said that the diagnostics showed that there was an oxygen sensor problem, but because the light was off when by the time I got there they couldn’t do more to cure the problem than that.


The next time, the light obligingly stayed on, but the error code still only said that there was an oxygen sensor problem; even after attaching the diagnostic computer to the car the tech was unable to pinpoint the problem to being this sensor or that one… or even to being a sensor at all, obviously.


My point being that the error code only serves to narrow down the range of problems, just as the “Service Engine Soon” only alerts the driver to a fault in the car’s emission-related electronics systems, a pretty broad warning. The same error code can still cover a multitude of problems and it takes a competent tech to diagnose and solve the problem.

That’s why we need good technicians even in this day of computerized diagnostics.

 

The EMC stores the error codes so there would have been an indication of the failure even without the light lit. I think your dealer might not have known how to read the stores error codes correctly.


OBD-II error codes ger very specific abot the problem. They are not general at all.

For example, here are error codes dealing with oxygen sensors.
P0130 O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
P0132 O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
P0140 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

Fairly straightforward right? You can tell which sensor, and what the problem is.
See more at http://www.obdii.com/codes.html

So, In my opinion, your dealer didn't want to pay for the parts and labor to replace a failing part right away.

Certainly good mechanics are required, but letting a customer drive away after the MIL light comes on without doing anything is not the behavior of a good mechanic in my opinion.

 

I have had several problems with my cervice engine light coming on. The first time the car went into limp mode. The dealer replaced the wiring harness. A few weeks later the light came on again. They determined the map sensors needed to be replaced. Guess what the light came on again a few weeks later. They replaced the DME.

I am picking up the car today. Hopefully it works this time.

 

“So, In my opinion, your dealer didn't want to pay for the parts and labor to replace a failing part right away.”

You’re right, Alan: The dealership didn’t want to pay for the repair at all. The service manager said after my first visit was that they read the OBDC for the stored fault code –- where did you get the idea from my post that they couldn’t or didn’t? -- but they couldn’t go farther if the light wasn’t on when I came in. That’s MINI/BMW’s policy, not the dealership’s and if they had replaced the sensors or DME then, the dealership would have borne the cost, not MINI. As MINI warrants the car, the dealership shouldn’t pay for covered repairs, right?

When I returned with the light on I watched while the tech read the code, then the post-cat oxygen sensor voltage readings, which he said oscillated far more than is normal. Unfortunately, it’s not always so simple as saying “This value is abnormal; replacing the post-cat oxygen sensor will fix the problem.”

That’s the first thing to try, but in this case it didn’t solve the problem. Nor did putting the new sensor in the pre-cat position; the sensor readings were still oscillating. The next step was to replace the DME, which did bring the sensor readings back into the proper range. It makes sense to replace the sensor first, as they fail more often (I hope) and are an order of magnitude cheaper than the DME.

I don’t need to defend this guy as a good mechanic; I know he is and have a pretty good ability to discriminate between a good mechanic and a lousy one. The dealership followed MINI policy; once I came in with the light on, the tech followed through and fixed the problem.

While I usually respect your opinions, Alan, I think you are wrong about this mechanic’s behavior.

 

After your new explanation of the procedures the mechanic went through, I now agree that you have a good mechanic.

It was your comment that after reading the ODB-II codes, that they couldn't tell which sensor was the problem where I went wrong.

Thanks for posting a more complete description. It helped me understand what your mechanic was up to.

 

I was understanding just like Trippy. What led me to believe that they either didn't know what they were doing or feeding you a bunch of bull stuff was that I understood that they said they could not determine anything if the light is off when you bring it in. Even if the light goes off, codes are still stored and can be retrieved.

Good luck,

 

I had this same experience when I was having problems with the throttle body. The 2nd time I took it in, the SES light was on when I made the appointment. 2 days later when I finally got there, the light had gone off. The dealer looked it over, and said that there was a code stored, but since the light wasn't still on, it must have been a temporary problem. BS, I thought. About 2 weeks later when the SES and EML light both went on @ 60MPH, dropping me into limp mode in heavy traffic, I drove straight in to the dealer. Since the light was on, they finally agreed there was a problem and ended up replacing the throttle body. That's been about 3 months and no problems since.