7B Activation, map cooling (ODBII:P1622)

[barksten]

I have a Z3 2.8 year 2000.
I bought a ODB-scanner and got the ECU fault code "7B Activation, map cooling (ODBII1622)".
When checking the ECU data stream I've noticed some weird values:

On a cold engine (>24h since running)

coolant temperature, engine [°C]	83.32
coolant temperature, radiator outlet[°C]	81
Oil temperature, engine[°C]	104.80
intake - air temperature[°C]	73.95

Starting the engine (idle)

coolant temperature, engine [°C]	87.38
coolant temperature, radiator outlet[°C]	81
Oil temperature, engine[°C]	103.93
intake - air temperature[°C]	74.23

Stopping the engine again

coolant temperature, engine [°C]	143.68
coolant temperature, radiator outlet[°C]	81
Oil temperature, engine[°C]	110.02
intake - air temperature[°C]	74.23

I can also stream some generic OBDII values which reads:

Engine coolant temperature	46°C
Intake Air Temperature	27°C

which to me seems more realistically.

My concern is the constant 81 on radiator outlet.
My guess is that it represents the sensor that looks like this:

I tried to disconnect the cable from the sensor but it still reads 81 in the scanner!

Does anyone have a clue and some suggestions how to proceed?
I guess I can try to find another sensor and connect it to the cable to see if I get some other readings...

 

[barksten]

I’ve talked to my local BMW shop and apparently the temp sensor is not available as a part anymore.
I suspect that the sensor is used for models with electrical fan but mine is not electrical (M52tub28). Maybe it’s inactivated in software and 81 is some kind of default value if it’s missing?

 

[Pingu]

Test the resistance of the sensor with the engine cold, and with the radiator warm in the area of the sensor. If they are different, the sensor is working.

BR/GR wire is a wire that is common to both the intake air temperature sensor and the coolant temperature sensor. It is a ground wire that goes to pin 39 of the DME conrol unit. It may also be your problem, as the air temp seems to be very high.

 

[barksten]

Some status update:
I replaced the thermostat and that fixed the ECU error code P1622.
The temp readings are still the same.