Okay --

My wife owns a R56 2013 Mini Cooper Base Coupe. She had P173B and P0128 CEL codes. I went to menu 7 and saw CTMP-MOM read *** so I figured it had to be the sensor. No problem. I went to Mini and bought an OEM sensor and replaced it.

It's been about two weeks and the check engine light is back on and CTMP-MOM is reading - *** again.

I'm wondering if anyone else has replaced this sensor and within a couple of weeks ran into the same problem.
Is there another underlying issue that could be shorting the sensor? Maybe it was just a faulty sensor? I'm not sure. Looking for advice!

She did drive for a day or two without the coolant expansion tank cap on. Could that have caused damage to the sensor? Thanks!

 

Well sons MINI was always breaking so he traded it in. I wouldn't have given up as he did but I would find a well respected MINI mechanic and let him/her have at it. If you know how to use a multi meter you can test the sensor, probably not bad but worth a shot.

 

If it hasn't been too long since you had the temp sensor changed, I would just go back to Mini and have them deal with it. If the new temp sensor is faulty, they should replace it again no charge. If they say it is fine, then I would expect them to find the real cause and to factor in what they charged me for the temp sensor and the inconvenience caused.

 

Yes, check with MINI and also check the plug side of the wire, these plugs can break apart or crack and then the pins lose contact.

 

I bought the sensor directly from mini, but installed it myself. I was going to ask if there's a warranty on the part itself, but I'm not sure theat there will be.

 

Did you bleed it?

 

No, but just changing the plug doesn't require a bleed. Is there some other benefit to it that could potentially cause the reading to fail?

 

Well, the temp sensor is pretty much at the highest point in the system. If there is any air trapped, it will likely stay there. And if the engine was not completely cold when you changed it, it most likely does need bleeding.

There is a plastic screw head right next to the temp sensor on the top side of the thermostat housing. Open it slowly and only a bit until some coolant comes out. Then run the engine and check whether the coolant level in the expansion tank retracts. If it does, repeat (and re-fill coolant if needed).

 

Thanks for the advice. I slowly opened that plastic screw and nothing came out. It was nearly all. The way unthreaded.. There is coolant in the expansion tank.

Does it need to be warm first? Or is this a bigger issue? Thanks for the help

 

Is the coolant above the minimum mark? If so, coolant should come out even if the engine is cold. Did you open the expansion tank's lid?

Note: this is not to say that the cause for the mis-reading is potential air in the system. It may well be a wiring or electronic issue as suggested above. Either way, if there is any air inside, it needs to get out.

 

Expansion tank is inebtween the minimum and maximum and yes I just replaced the lid, actually. And I agree the air does need to escape either the way, but yeah nothing is coming out

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At this point I would try filling the system with coolant until it comes out of the bleeding screw. Then close both the screw and the lid, run the engine for a few minutes and check whether the coolant level retracts to a lower level. If it does, repeat from start.

 

Alright, I'll try it out. Thanks!