Here is the skinny, bought a 2009 Mini Cooper S (R56) to rebuild and sell, I am done with the rebuild, and everything went swimmingly, but now that is all running and happy again, I intermittently get a combination of the following 3 CELs; P0117, P112B, P173B. Now I have replaced the Temp sensor, ran continuity checks on the temp sensor wires all the way to the main harness while doing a wiggle test. Double and Triple checked the routing of the coolant hoses, and nothing is jumping out as a problem.

I took temp readings on the hoses, at the block, at the radiator (both in and out) and did not see anything alarming, Block and hot side of radiator never exceeded 150F, even after allowing the car to warm up for an hour followed by some pretty spirited driving. Cool side of radiator never exceeded 100F, hot side of the coolant lines at about 121, cool side at about 95F.

I Ohm'd the old temp sensor and it was within spec, about 4.8 ohms while being held in my hand during the reading. I am beating my head against the wall here any input is much appreciated.

FYI, the thermostat, all coolant lines, and water pump are all new. Radiator is about the only thing on the coolant system not replaced.

 

Hello, so i have somewhat the same issues on my 09 MCS. P0117 and P112B. Radiator fan turns on immediately and stays on after shut off even if it was on for just a minute. Pretty sure it's going to be a coolant sensor on the thermostat since it's not leaking and coolant level looks good. Have you resolved your issues?

 

I did, it ended up being a loose connection to the temp sensor, I found out after replacing it, and still having the same problem. Basically I used a dental pic to bend the pins in slightly to make better contact. After that the CEL light has not come on since. Good luck.