Hey guys, hope y'all are hanging tight with Covid and all. It's been awhile since I last posted, but I've run into an oddity here. Long-ish post warning! First, some recent history (my car is a 2009 JCW):

1. Mid-June: Walnut blasted
2. Same time: Changed water pump to address coolant leak. Replacement method: lowering/raising engine after removing engine mount without removing the friction pulley. Just removed WP pulley, then WP.
3. Test drove no issues, no codes
4. When parked in garage, a bigger coolant trickle, so changed coolant pipe (it had cracked). Removal method: removed airbox, lowered intake manifold (i.e. didn't remove from engine bay), removed thermostat housing. Burped the coolant system.
5. Took it out for a proper test drive - when I fired it up, code P0118 / P0118PD appeared, so I thought hey, sensor dead, easy peasy, right? Nope. This is where I'm stuck...
6. Engine starts perfect, not rough, heater blows hot after warming up, which are not symptoms of a bad CTS, IIRC. I'd clear code each time and code returns on start-up.
7. Swapped out previous CTS with new one just for kicks - no dice - same issue, so back in the older one goes.
8. Also found blown 7.5A blade fuse in engine compartment (fuse diagram shows something engine-related, but not sure exactly what). Replaced with new, and blew again. Bad ground? Short? But where? The only ground I know is the big one by the top-left engine mount, which I removed for the WP job. It was properly re-installed.

I don't know how to proceed. The radiator fan runs great, just goes into fail-safe mode everything P0118 pops up, so it runs regardless of whether the engine is cold or hot, but shuts down after about 5-10 minutes when engine is off. Any advice would be appreciated:
- Anybody experienced a problem like this before? Would appreciate your assist.
- What is the proper way to test the CTS with a multimeter - can you backprobe (I don't think so in this case)?
- What about the wiring harness? Does it start from the CTS and routes directly to the ECU or does it traces further/somewhere else behind the engine?

Thanks in advance!
- Aaron

 

Your moves so far sound good. You said the heater gets hot; what about the rad? Is the thermostat functioning? Does your code reader give you coolant temp?

If you are blowing fuses, there's a problem. It may or may not even be related to your codes, but it's still a problem that should be fixed. (Please don't plug in a higher-rated fuse to stop it from blowing unless you like car fires).

After verifying that the thermostat is good, next thing I would suggest is check the wiring diagrams to see what that fuse does. Then you can start troubleshooting that issue. Electrical stuff gets complex quickly - I try to write down all the things I changed or tested to keep from getting confused, and undo steps I took that did not solve the problem.

 

Maybe you swapped a plug? There are 2 or 3 in that area with the same connector. I've also read an open ground wire will cause this, check the harness.

 

I'm getting a better code reader this week and hopefully that gives me temp readings. And yes, electrical stuff racks my brain. It'd be awesome if someone had a wiring diagram for these fuses and harnesses easily available.

 

The single wire in front, double for the CTS, right? And on my JCW, I think those those connectors are color-coded to match the sensor connectors!

 

Where do I find a wiring diagram or specific fuse diagram for the auxiliary fishes in a 2012 Mini. The fuse diagram on the cover, shows fuses and relays that are not currently present. There is a minor loss in power, mpg, and the engine gets fairly hot but i can’t tell if that is due to the fuses or not since I can’t tell what they do.
I am missing FL7, FL10, FL12 and R4. The images related to these fuses look important but if the car works then are they necessary?

 

Your fuse that’s blowing is F7 Crankcase breather heating relay

 

Hello. I am a new member, and found this thread. My son and I just bought a 2003 Mini Cooper as a project to learn mechanics of a car. we are experiencing exactly as described. Getting P0118. We changed the sensor, however the fan is still on, long after the car is turned off - maybe 10-15 minutes after the car stops. And, it turns on, even while the engine is cold, at first start. May I ask what the solution to this problem was? Thank you in advance for taking the time to assist us.