URGENT HELP! E46 water temperature gauge

[onemillionclub]

Fellow bimmers,Yesterday evening, when I started my car engine, d water temperature gauge suddenly shows to d MAX but so hairannya my car engine was 100% cooled (coz' parked since morning).The red light on the gauge dissappear after the engine start but the needle still shown to d max..I decided not to drive it and wait until this morning to see whether the problem still there..Bad....it still there....but my car engine is 200% cool....Need you guys help!:dontknow:

 

[M3addict]

i've experienced this once....temp at max and red light turn out but my car cant start at all...
send to workshop (towed) n the mech said ned to change key + ews + ecu....but i think i get conned;..so be careful...
better go check at reputable workshop

 

[jarance]

Engine Coolant Double Temperature Sensor
The temperature sensor is screwed into the cylinder head. A varistor (NTC = Negative Temperature Coefficient) serves as the measure for the coolant temperature.

Among other things, the coolant temperature serves as a measurement variable for following functions:

Start volume calculation

Injection volume calculation

Set idle speed

Characteristic Map Cooling

In the event of the engine coolant temperature sensor failing, a fault code is entered in the DME control unit and a substitute value is calculated from the value of the intake air temperature sensor with the aid of a temperature model.

The housing of the coolant temperature sensor contains two sensors (double temperature sensor). The one sensor sends the signal to the DME control unit while the other sensor is connected to the instrument cluster.

 

[M3addict]

think i've got conned... :stupid:

 

[xcrave]

LOL... based on what ive read... its your Temp Sensor located at the bottom of your expansion tank...

REFER Item #20

When the thermostat failed it will give a false reading and will increase pump speed, will interfere with ALL of your car electronic...

this will then produce all sort of problem as the car work harder to reduce temperature of the "false" high temp.

HOW THE THERMOSTAT WORKS?

*When the car is producing heat the thermostat will "open" by stages signalling to the waterpumps, fans and such to increase speed...

When the thermostat is "Stuck" on "Open" stage it will give the highest reading and then force every related item to increase cooling... dont ignore this it may kill your UDM!!!

My bet 100% will be on the T-Stat that son of a gun is always there to ruin a good car

Get it changed and then you decide on other things... it will not cost you as much as all those ECU +++ changes....

 

[jarance]

bro, item 20 is the level switch/sensor. it is not the temperature sensor.

The correct item is #9. see below.


Water hoses - BMW parts catalog

 

[xcrave]

Aiya not the #20 yeah ... iskh thats the water level sensor... soli2 got mixed up i guess... was thinking about my own problem last time about the radiator light always own last2 is the level sensor faulty


BTW air bubles in the coolant also produce this...

wahhh thanx for Sifu Jarance for the heads up

Also there is 2 other items you need to check these are the items

This is the stuck "open" thermostat i was refering to: ignore my previous posting thats if you have radiator warning even with full coolant and bleed complete the procedure...

Location is here:

Item #10

Item #4 also here