Try to correlate relative outdoor humidity & temperature for the 12 hours prior to your seeing the half'n'half light come on. Might help techs diagnose what the cause(s) are.

When my '07 S exhibited this it ran terribly, if at all. Over the 5+ years & 97,000 miles I drove that one that particular fault was evident only before an 'improved' crankcase breather / valve cover assembly / intake manifold was installed. That all was part of the improvements built into S's beginning in 2010 from what I was told.

I learned there's a myriad of causes behind the yellow outline CEL light after experiencing it a dozen times in the last year with that S, then again with a brand new non-S Clubman I traded up to early last December. 'Parently it's a 'known issue' on a few vehicles, they think it's software & are working on a fix. Now that we're beyond the 20 degree & below temps for the season I'm hoping the CEL stays off until the fix is Federally approved (affects emissions approval) and installed....

 

The gas cap seal can be compromised in below freezing weather, and especially if humidity is high or it rained/misted/snowed the night previous. If there's water/condensation build up around the gas fill metal snout it will freeze there overnight, expand the gap between the cap and snout and cause a vacuum leak which the engine will notice.

 

Well in my case, being Texas, it was close to 80 degrees outside when it came on, and the previous night it did rain, but didn't get below 60 degrees. I'm starting to wonder if the quality of gas could have caused the light, since the day before I was down to two lights on the gas gauge, put some gas in from Walmart (non-Top Tier) because it was closest to where I was at the time, then the next day I have this pop up. Prior to this I'd been running gas from Top Tier stations for probably 6 or 7 fill ups.

 

The exact same thing happened to my 07 MCS on the freeway onramp today, it was a warm California day. I always allow my Mini to warm up for 5 minutes before I start driving it. As I was merging into my lane all of a sudden I felt power loss even (yellow engine light on) though I was babying it like I always do until it reaches operating temperature. It was run rough as well, this took place for only 5 seconds. I thought it was going to stall.

I had about one gallon of gas in my tank and oil was at the middle point between min and max, could this have anything to do with the power loss? It never happened again since then.

 

It's happened again. Was off when I left to make a two hour trip, and as soon as I got on the highway and started to accelerate to change lanes (not aggressive, just normal acceleration), and it stayed on the whole way up north. No other lights were on, but I could definitely tell that it was down on power based on throttle response in 5th and 6th gear. Right before getting to my hotel, it turns off and stays off until I have to leave for a final, and again it comes on as I'm accelerating to change lanes on a highway about an hour after it had turned off. Both times it was over 80 degrees ambient temp and humidity was up, though I don't know exact percentage. It's stayed on since coming on this afternoon and I have no idea what is causing it. No other lights are on, no odd sounds coming from the engine, nothing. I do know it probably needs new plugs and I'm going to have the 90K maintenance service done this week since I've still got the extended maintenance program on the car, so we'll see if that plays into it or not.

 

Well, I guess it's my time in the barrel.

Warm weather here (80s), some brief light rain yesterday (car parked in driveway).

Last night as I was on my way to meet a friend, I heard (and felt?) a "pop" sound. The car almost immediately began running rough, and could smell sulfur (MINI Beelzebub?). Not sure if the pop was a valve/butterfly/throttle body slamming shut, or simply a gurgled back-fire.

Pulled into the parking, check under the hood, everything looked normal (my immediate thought was a loose spark-plug wire). After about an hour and a half, I went out and started the car. CEL (yellow outline) came on. Car was running very rough, with a VERY rich fuel mixture (lots of sputtering, difficulty maintaining idle, very low power). I limped home (10 miles), and sent an email to my SA at the dealership to be prepared to receive/fetch the car.

2009 MCCS, 33K, MINI warranty expired 5 weeks ago (I do have a GMAC extended warranty).

 

Sounds like a turbo hose blew off somewhere. Check all your turbo piping and every connection from the turbo all the way to the intake manifold. A blown off/slightly off charge pipe will cause idle issues and sputtering and will make a loud pop when it blows off. Pretty common in a lot of turbo vehicles.

 

Yeah, that was one of my first thoughts, too. I didn't see anything in the hot engine bay last night, and I can't see anything "off" this morning.

 

the intake manifold pipe is way back there, also check the blow off valve pipes, and intercooler pipes which are down below...some of these you cant readily see but could be slipped off just a hair.

 

Out of the barrel (sort of).

High pressure fuel pump failure. Covered under MINI's extended warranty (emissions control) coverage. 10 years/100,000 miles.

We are now discussing the $200 towing charge.

 

See I'm at just over 93K miles and when I get my light, I'm usually accelerating on a highway and shifting from 4th to 5th at around 4500-4800, which I'm inclined to believe is the fuel pump on the way out. I just wish there was a way I could get it replaced by the dealer under this warranty regardless before I reach 100K miles and become really screwed.

 

 

So it's 120K not 100K? Cool!

 

Indeed. My error. But that letter ONLY refers to 2007-2009 Gen 2 MINIs.

 

So I believe my throttle body is getting stuck but it only happens when its warmed up all the way. when the car it cold it runs fine. its goes into limp mode with codes p1497, p0507, p1638 and p1637. Does anyone else have any other ideas. I checked for leaks and I couldnt find any.

 

Strange, the only time my throttle got somewhat stuck is when it was below freezing. Warm weather isn't a problem.

 

?soo.. to bring it up to speed. was in 4th doing about 65 passing someone and bam.. no power. got off the highway, had it towed. the dealer says they can either "clean" the throttle body or put in a new one. "cleaning" it is 200.. putting a new one in is 200 plus 350 for the part. i'm relatively handy and have cleaned throttle bodies before on a truck i had. question is.. is the dealer going to do anything other than take it off, spray it, and put it back on? next question.. is there anything from preventing this from not happening again.

I'm fairly certain I can buy a throttle body from ECS and install it myself for 250.

any thoughts?

 

No power? Was it undriveable? If so then a dirty throttle body is not the answer. So much BS in their diagnosis.

 

barely. it was able to get me off the road. it had a jumping idle so i turned it off. when i turned it on 30 minutes later it idled fine but the light was still on and no power.

what are your thoughts?

 

Have you had your vacuum pump replaced? If not, I'd have the dealer inspect it for leaking oil and then inspect the vacuum lines that run from the pump back down under the intake manifold to a pressure reservoir and pressure converter. If it's anything like my case, which sounds similar (punch the gas to pass and the light comes on after falling on its face power-wise), the vacuum lines are swollen from heated oil and not allowing boost to build between the pressure converter and the wastegate of the turbo.

 

let's start by finding out what codes were thrown. and the half power codes.

 

I'll check with the dealer tomorrow. There's another CEL issue that needs to be fixed either way for inspection.

I suspect it was the frozen throttle body as it was below freezing right around zero for 3 days.

 

Well my 09 Clubman with 71k on it has thrown the half yellow engine light last night. It has done it about 2 months ago and not since until last last night. I knew this could mean loss of power which I had not felt when the light came one so I pushed it a little for a second or so, felt the lack of power. Pulled off, turned car off and right back on and it was fine. No light, normal power. The first time it did this they wife had let it sit idling for 30 min when she just turned it off and back and and the issue was gone.
So now this makes two times since we have had it. Odd that just simply turning it off and back on that it is then ok makes no sense to me. She has been putting top grade gas in it, from lousy stations, so I told her to stop that, AGAIN, so we will get good gas in it and see what happens. Car runs fin otherwise. I hate cars that do sporadic crap!

 

When was this released???? Would this apply to my 09 Clubman S? Losing power when the half yellow engine light comes on.

 

That notice came out in 2010, IIRC. It's specific to the High Pressure Fuel Pump, but if that is the cause of your trouble, then yes.