Code 8C: MAP controlled thermostat circuit control?

Getting this code with 1C and 1D, lean idle mixture on both banks. Any ideas? Thermostat was replaced at 70k in 2009, car has 103k now.

Defective thermostat? What coolant temperature does your cluster report?

Thermostat was replaced about 40k miles/3 years ago, for what its worth. I havent checked the water temps yet. Guess I will do that next.

So I just checked it and its reporting 44*C, but thats with the car off. It is unusually warm here today, about 70*F, and I had started the car and let it idle for just a few minutes before I did that. But, is there no way to check the temp while the car is running? After I get the OBC unlocked, how do I start the car to run any tests?

you can unlock the cluster with car warmed up. Test number 7 Coolant temperature should be around 93 Celsius.

http://forums.bimmerforums.com/forum....php?t=1241963

Originally Posted by energizedmortal

you can unlock the cluster with car warmed up. Test number 7 Coolant temperature should be around 93 Celsius.

http://forums.bimmerforums.com/forum....php?t=1241963

Thanks, but why is there a velocity test?

test number 8 will show km/h (current velocity)

If the car isnt running, the velocity will be zero!

Originally Posted by Studawg

After I get the OBC unlocked, how do I start the car to run any tests?

This is what Im trying to figure out

turn the car on first, and then unlock the cluster to run tests.

Oh, the instructions I read said the key had to be in position 1.

So my core temp, according to the OBC, got up to about 104 C on a 2 hour drive, (it was about 70* F ambient) but never more. Gauge needle never moved. Ive still got the 3 codes. Any more ideas?

Originally Posted by Studawg

So my core temp, according to the OBC, got up to about 104 C on a 2 hour drive, (it was about 70* F ambient) but never more. Gauge needle never moved. Ive still got the 3 codes. Any more ideas?

For a v8, I think your KTMP is fine.
Not sure what your codes. Can you post them detailed? Are these Peake? If so, post the whole thing. First and 2nd part (table & number). What you posted doesn't make any sense.

Table OF

1C Mixture Control Idle Cyl 1-4
1D Mixture Control Idle Cyl 5-8
8C MAP Controlled Thermostat Circuit Control

Originally Posted by Studawg

Table OF

1C Mixture Control Idle Cyl 1-4
1D Mixture Control Idle Cyl 5-8
8C MAP Controlled Thermostat Circuit Control

the first 2 codes point to a lean condition: check for vacuum leaks, clean the MAF (and test it). Check the age of the O2 sensors.

The last code is BMW specific code - your T-stat is toast.

On the 540, Make sure to check the harness where it plugs into the stat. There is a known issue there that can even lead to a engine fire. Check your plug to make sure its not loose and falling apart.

Max

Thanks for the responses.

I checked for vacuum leaks before and found a couple and fixed them. I have a new CCV, but I didnt replace it yet because after I fixed the vac leaks it started running a lot better. Maybe the CCV is the source of another vac leak?

I cleaned the MAF with MAF cleaner already, but didnt test it.

All 4 O2 sensors were replaced by PO at 100k.

T stat was replaced at 70k in 09, time to replace again?

Question: When I first start the car in the morning, it fires right up, and idles smooth. Then about 45 sec later, i hear something that sounds like a gurgling sound, and or a valve closing, then the idle speed goes down a little, almost too much because then it starts idling a little rougher. Any ideas on that?

oembimmerparts--I had already checked that plug and it looks ok. I didnt disconnect it though.

bump