CSL Water Temperature indication too low

[Jetcat]

Hello,
Can anybody give me an idea what can be wrong on my CSL since suddenly the water temperature gauge went on the track to near blue scale with a normal oil temperature of 110 degrees celsius.
We changed the thermostat and one temperature sensor and still have the same problem with temperature fluctuations.
It looks like erratic indication since I can't believe a water temperature in the near blue section with Vmax on the highway nor with 7900 rpm on the Hockenheimring.
Thanks for your ideas since I am lost...

[NZ_M3]

Use INPA or the guage cluster hidden menu to see if it is showing digitally the correct temperature - if it is then it's the stepper motor on the cluster that's packed up. If it read low still then something else is going on.

[NBTBRV8]

Presumably it still has coolant in it? As normally a cool reading is an indication of coolant lose as the probe isn't immersed.

[patphnx]

Use INPA or the guage cluster hidden menu to see if it is showing digitally the correct temperature - if it is then it's the stepper motor on the cluster that's packed up. If it read low still then something else is going on.

Sorry if this is a dumb question...but what's the hidden menu and how do you get to it? Is it different for the menu with the Oil, MPG, Outside temp etc?

[Jetcat]

Thanks for your answers.
I would like to know more about this "hidden menu" since I have no idea what it is.

[phoenixcsl]

You can get to the hidden menu in the cluster as follows (details taken from M3 forum.net a few years back)

This is for unlocking the instrument cluster.

THE LIST:
=========

Instructions to access the hidden OBC functions:
1. Hold Trip Reset while turning ignition key to on position
2. OBC should show "Test"
3. Use Trip Reset to select function 19.0 that unlocks all the features
3. Wait for display to show "Off"
4. Depress Trip Reset for 1/4 second and release it
5. With no delay press Trip Reset several times to select one of the following function s
==========================================


BMW E46 On-Board Computer (OBC) Hidden Codes
nr example description
1 Car Engine and cluster data
1.0 46nnn Chassis nr/VIN serial number (last 5 digits)
1.1 4nnn K-number
1.2 690236 Cluster Part #
1.3 045210 Coding (04)/diagnosis (52)/bus index (10)
1.4 1200 Week (12)/year of manufacture (2000)
1.5 09_160 Hardware (09) and software # (16.0) of cluster
1.6 Not used
1.7 04__44 CAN-version (04) KI-revision index (44)
2 (test) Cluster System Test - Activates the gauge drivers,
indicators and LEDs to confirm function
3 SI Data
3.0 1098 Used fuel in liters since last SI (Service Inspection)
3.1 0231 Periodic inspection days; elapsed days (since last SI)
4 Momentary Consumption
4.0 0145+ Instant fuel consumption - 0145=14.5 liters/100km
4.1 0018 Instant fuel consumption - 0018=1.8 l/Hour
5 Distance Gone Consumption
5.0 082 Average mileage; 082=8.2 liters/100km
5.1 0536 Calc. km to refuel (momentary distance to go)
6 Fuel Level sensor inputs in liters
6.0 109330+ Fuel level averaged; Left half sensor input=10.9 liters; Right sensor input=33.0 liters
6.1 0439+ Total tank level averaged; vlgs 6.0: 10.9+33.0=43.9 liters
6.2 0442+ Indicated value (44.2) and tank phase
7 Temperature and Speed
7.0 021+ Coolant/Engine temperature (2.1C)
7.1 130 Ambient/Outside temperature - chg met 5 pts. 125/130/135
7.2 + Engine speed / Current RPMs 1/min
7.3 + Vehicle speed / Current Speed in km/hour
8 Input value in HEX form
8.0 1d0+ System voltage ADC-Value Hex code
8.1 26C33C+ ADC Values HG left/HG right
8.2 0000 ADC Value brake degradation sensor (000=o.k.)
8.3 18C ADC Value outside temperature
9 Battery
9.0 140 Battery Voltage - 140 = UB 14.0v
9.1 242013+?
9.2 074_78+?
9.3 0011+?
10 Not used
11 Not used
12 Not used
13 GonG Gong Test
14 Not used
15 Status cluster I/O-ports (bit codes) 0=low; 1=high
1st-belt contact, seat belt fastened=0; 2) ignition lock contact, key inserted=0; 3) door contact, door open=0; 4) clock button pressed=0; 5) SI reset=0, for reset=0; 6) EGS transmission failure=0
Status Digital Outputs (bits) 0=inactive, 1=active
1) Gong output; 2) Brake warning lamp; 3) Low fuel warning lamp; 4) EGA lamp; 5) seat belt lamp; 6) manipulation dot
16 Not used
17 Not used
18 Not used
19 Lock Status; unlocks functions in range 3-18
19.0 L-On/L-Off Unlock: press button when "L-Off"
20 Not used
21 Software Reset; reset OBC settings
00 End of test

[Rick H]

Worth adding as a Sticky ?

[Jetcat]

Thank you

[Jetcat]

Hello,
I changed the thermostat, all water temperature sensors, checked the temperature in and out with BMW-laptop, no fault found but with low rpm the out-temperature is around 45 degrees and 80 degrees in.
With high rpm, both read 80 degrees.
Looks like something lowers the water out temperature too much.
I have no more ideas...

[Monkey]

Do you have any fault codes stored?

The oil temperature would also lower if the coolant was indeed that cold, but if the oil is running normal temp you could be looking at an electrical issue.

[Jetcat]

No fault stored.
After changing the termostat a second time, still the same.
Since we now changed nearly everything, we are going to change the visco, so the whole cooling system is nearly new.
Regards,