i just bought a 2007 Cooper S, and my car seems to be running too cold.
i accessed the hidden service menu in the Tach and it is reading 86-91*C for coolant temp, under all driving conditions. i know 100-102*C is supposed to be normal operating temp. the car runs great aside from getting about 3-4 mpg less than my buddies identical MCS under similar driving conditions. i suspect that is in part because the ECU is continually trying to get the engine to operating temp. it has thrown the P0128 code a couple times.

what would cause this? stuck thermostat? non-OEM 180-190* thermostat? the dealer mentioned something about a shop changing the ECT sensor, i can hear bubbles in the coolant passing through the heater core right now. gonna try to rebleed it today.

any other ideas?

 

* MINI DTC P0128 (0x2F07) - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
Looks to me the electronic thermostat would be the thing I'd start with first.
The ECU is seeing that the temperature is not up to specification as read by the Coolant Temperature Sensor (CTS).
Unless the CTS is giving a fault reading, therefore the ECU thinks the engine is running too cool.

- Erik

 

where would i find a fault reading for the CTS?

 

You would want to take a known measurement of the coolant temperature with a separate probe not hooked up to the car and compare to the CTS reading.
If they differ, the CTS is faulty.
If not, then you're looking at a thermostat.

- Erik

 

cool, seems simple enough. wonder if a temp probe in the coolant reservoir would do it?

 

Better cold than hot.

 

I thought these engines did away with the disk type thermostats and use a computer controlled servo to decide how much coolant to flow... If that is the case, would it be a thermostat housing due the computer can't reduce the flow to bring the temp to the correct value?
E

 

Double post... Oops!

 

kinda. if its running rich all the time perpetually trying to heat up the car, thats not ideal. kinda like the low temp performance thermostat scam...

 

Correct, and there's a two stage flow system.
"Low-flow" for daily commuter to keep the temp at the 215deg range.
The "high-flow" for when the engine is under high load, to drop the temperature.

Sounds like in blunderbird's case, the thermostat is stuck in high-flow all the time and therefore requiring replacement.

- Erik

 

pretty much exactly what i suspected, just didn't know thats how the thermostat worked...

thanks for the help!

 

swapped out the thermostat and temperature sensor, now the car is running in the 105-107*C range.

 

Yeah but you are just burning fuel in that case. If it was the other way around headgasket and blown radiator would be in your future.

 

P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) popped up at 7800 miles so I took it to the dealer. The SA told me that while my VIN was not in the range for the campaign to replace the coolant temp sensor, the coolant temp sensor was the likely culprit. (mine is a 4/2012 build.) And the notes from the tech say faulty temp sensor, replaced.

 

R56 Hidden menu temp shows CTMP-MOM +++oC
OBD temp never goes past 84C fan runs all the time
throws code 2f18 coolant temp sensor,signal -but thermostat been changed twice - must be coolant temp sensor wiring no ? --driving me crazy

 

Sorry. I know this is an old thread but I'm currently working on my R56 1.6 cooper. It was running cold. Hottest i could see on an icarsoft computer was 70C when racing as fast as i was able up steep mountain switchbacks for 10 mins after climbing a mountain dual carriageway for 5 mins at speed, with the car running warm already previous to that.
I changed the thermostat which came with new CTS's No change. This evening i went for a little mountain run and 48C was the max. It was frosty but still. Way home included a steep uphill for at least 5 mins after a 5 min downhill and the engine slightly warm from the drive there a few hours earlier.
I suspect the cam timing is running retarded. I recently changed the timing chain and tensioner but now it's slapping again. I suspect i was sold the old style chain tensioner. However i first wanted to change the oil and thermostat. The oil was smelling of fuel as the car is running so cold, i thought some fuel must have seeped into the oil from the extra rich mix. Next step is to try to find a better tensioner and see if it helps. Failing that perhaps there is something else come loose or something, I'm ruling out slippage on the bottom bolt due to the chain slap, assuming the tensioner must not be doing it's job correctly but now i'm temped to take the valve cover off.
I'll order a tensioner and if i get time i'll remove the valve cover to check the chain from above. Do the vanos valves also tension the chain?
Thanks.
izz

 

Hi. Did you ever find out what it was? I've just noticed some damage on wires close to the exhaust manifold cover on the right side when looking. I might also check here myself next.

 

My 2009 Mini base was running cold. Replaced the thermostat and did a few coolant bleeds and the temperature is normal now. Appears the thermostat was stuck.