Hey guys, new owner of a '11 cooper s in horizon blue. Random check engine came on about 3 days after purchase of car. No performance issues, just a slight rough idle. Pulled negative terminal for about 1/2 hour. Reconnected check engine light went away. But came back a few hours later. Scanned car, 3 codes for bank 1 running lean only looked at 1, it was lean at 9% throttle @ 1400rpm. Tried ecu reset again. Check engine never went away this time. Long story short. Called dealership to get things taken care if. He did some research and a Full tank of gas was promised by dealership upon purchase of car. I guess the service tech put it to full with 87 by accident. He believes this is why its running lean. So I ran the car to gas light and put a full tank of 93 in it. I have about 50 miles on this tank and its still got the slight rough idle at startup. Anyone have ideas? Is this not a gas problem?

 

Run another tank through there and see if it clears ups. If not back to the dealership for them to fix it.

 

It could take more than 1 tank? I figured as soon as it got a taste of 93 it'd clear up. Ill keep driving it and see what happens. Thanks for the advice.

 

And you didn't figure to call or visit the dealer for complimentary warranty work?

Because removing power to the ECU doesn't clear fault codes.
Those faults are stored in the non-volatile memory of the ECU and only can be cleared through a scanner.

What were the EXACT fault code numbers?

How did you try to "reset"?
Again, only way to clear codes is through the use of a scanner to remove them from memory.

Honestly, doesn't sound like a gas problem at all.
And if too low of octane was used, you wouldn't see lean conditions - typically you would see too rich condition...
Why so? Because the ECU is seeing auto-ignition (knock or "pings") and will dump more fuel into the combustion chamber, along with spark retardation to counter-act it.

My suggestion: Scan, record faults, head to dealer, have them sort it out.

- Erik

 

The scanner we used wouldn't let us reset codes. It kept saying unable to reset data. And yes, I did call the dealer the next day after it came on. Pretty sure I said that in my post. And I will find exact codes if I can today.

 

No Mini or BMW tech would put 87 in a car. All cars made by BMW (including Minis) are recommended to use premium fuel so they never put regular in any of the cars on the lot. Pretty hard mistake to make.

 

Wasn't bought at a mini dealership. It was a trade in at a jeep/dodge dealer. Was taken to mini dealership for inspection to make certified pre owned vehicle. Then returned to jeep/dodge dealer. They are the ones who put 87 in it. Code is p0171.

 

What model of scanner did you use, for archive purposes?

* MINI DTC P0171 (0x2BC0) - System Too Lean (Bank 1)
Well, the ECU is seeing a too lean of fuel condition and it's registering through the pre-catalyst oxygen sensor.
That could be several items including loose intake / exhaust components, etc.

Again, we encourage you to head to the selling dealer and have them work with a MINI dealer in the area to have it checked on their dime.
You purchase agreement will have the details, that's also not including the MINI's manufacture warranty.

- Erik