I have a 2010 R56 hardtop, base model, with about 67,000 miles. In 2013 I installed an UltraGauge which plugs into my OBD-II connector; I have it set to display my coolant temperature.

Since then, my coolant temperture typically runs around 200-224*F (93-106*C) under normal driving conditions. I have noticed if I start driving the car hard while the air conditioner is running, then sometimes the coolant temp will temporarily drop to 170-178*F (77-81*C), but it always goes back up to the normal range if I slow down.

Today, after starting the car I noticed the temperature went up to the normal temperature, but then quickly dropped back down to around 170-178*F (77-81*C). This was while driving moderately at normal highway speeds for an hour or more. Outside air temperature was around 85*F (28*C) but I did not have the air conditioner running. Except for a brief period after warming up from cold, I did not see a temp above 178*F all day. So something seems to have changed.

Does this indicate some kind of problem -- or not? The car is running great, no check engine light or warning messages. Without the UltraGauge, I would be totally unaware that my car has decided to start running at a lower termperature than it used to do. If the car's computer detected a problem, wouldn't it trigger a warning light?

Should I pay for diagnostic work to see if there are any hidden codes, or should I wait and see what happens?

BTW it is about a half-day drive to the nearest MINI dealer. I do have a local shop that seems to be competent, but...? They replaced my thermostat in 2016 at 51.8k miles. The first one they put in leaked, so they put in a second one. Is it unusual for a 2010 R56 to need two thermostats in 67,000 miles?

 

Are you running in Sport mode? Supposedly that drops the temperature setpoint as well.

The thermostat are kinda crap, TBH, and at least on the N18 there were multiple iterations to fix issues. It's possible it's gone into fail-safe mode, but I'd think that would show a check engine light.

I don't know if it'll help in this case, but probably worth the money to buy or borrow a Mini-specific code reader to see what's going on if you plan to keep the car: I am sure you''ll use it again. Bimmergeeks Protool works well if you have an Android device.

 

@Gubi , thanks for your reply. I have read that turning on Sport Mode can contribute to the temperature control system switching to the thermostat mode that results in lower temps. Some say this happens when the fan control switch is set to high.

I put my MINI in Sport Mode pretty much every time I drive it. That was true for the several years when my "normal" operating temperature was 200-224*F, and was also true yesterday when my car decided to start running at 170-178*F. I did play with the fan speeds yesterday; also AC on and AC off, but the engine temp never got above 178*F.

I will look into getting a code reader. My repair shop claims they can read Mini codes, but who knows? On the other hand, it is a very well equipped shop, and I suspect they do have a lot of the latest technology and training. So maybe their tool will be more capable than something I can afford to buy at the diy level? However they do it, a couple of months ago my Check Engine Light was on, and they charged me $165 for a "Computerized Engine Controls Test."

I have no Android devices. Can anyone recommend a good code reader for Mini Coopers which are either stand alone, or will work with an iPhone?

Hypothetical: IF no codes can be found, then is it safe to assume there is no problem?

 

On the iPhone I used to use an app called Carly that seemed to work okay for the MIni, but that was a while ago. You'll need a wireless adapter. It was a bit of a PITA to get it all set up and working with the iPhone wirelessly but, again, that was a while ago so maybe it's easier now. I prefer wired just for ease of use but I don't think that's an option on the iPhone.

As a standalone I had a Foxwell NT530 for my other car that worked well. I believe the BMW version will work with Mini but you should confirm this. If your guy is charging $165 for a code read then it'll pay for itself the first time you use it.

 

The Carly app gets good reviews, but at this point, I can't justify paying $99 every year for the subscription.

Just ordered a wireless OBDII transmitter for use with the BimmerLink iOS App, which, I am told, does not require a subscription.

I still have this question in my mind:
If a good code reader does not show any codes, is the lack of codes a reliable indication that there are no serious problems?
That is, Does a car like my 2010 R56 Coupe have enough sensors and sufficiently sophisticated software to flag all reasonably expected problems with some kind of code?