hi everybody,
I have this error from the ECU:
1223 Water Temperature. 

I tested the water temperature sensor, and i think it works because at 15 degrees it gives 3K of resistence and the resistence value goes down if i warm it with a lighter. 

The radiator fan works. It stars when the engine temperature is high!

But the arrow of the temperature water guage is in the red part (shows high temperature) when the engine is cold! As soon as i switch On the ignition!

What could be the problem?

I have a K100RS 1991. 

Thanx

Hi Old Boy.

It would be a big help if we knew what model and year K you have. There have been a few changes over the years.

Perhaps even add it to your signature, that way the info is always there for all to see.



Just read your intro that shows your model and year, but the info above still stands as not everyone reads the intros!

Sorry...K100RS 1991 😄

First of all,  Which sensor are you testing when you get 3K ohms at 15C?  Is it the one in the water pump or the one behind the radiator?

The water temperature gauge gets it's signal from the sensor on the bottom of the water pump.  Quick test is to pull the connector from the sensor.  If the gauge stays pegged in the red the problem could be the insulation has been rubbed off the wire someplace and it is shorting to the frame.  If the needle goes to the blue, then the sensor is probably bad.

Te sensor behind the radiator is a two part unit.  One part tells the fan to run, which you say is working properly.  The other part tells the Motronic engine control what the water temperature and thus the engine temperature.  The Motronic unit uses the water temperature signal to decide how much the mixture needs to be enriched.

A problem with that signal could result in an overly lean mixture for a cold engine or an overly rich mixture for a warm engine.  Lean will result in hard starting, and rich will give you black, sooty plugs and poor fuel mileage.

Thank you very much Point Seven Five!

So...i tested the sensor behind the radiator, i will test the other sensor as you say. 

If the fan runs means that the other sensor behind the radiator is ok?
Or is it possible that one part (to the fan)works and the other part (to the Motronic) doesn't work?

I think the mixture is rich because i have poor fuel mileage and i have a bad smell coming from the exhaust...i think is fuel unburned

The engine temp sensor on a 16v engine is only 1 sensor, all the things that happen are worked out by the Motronic unit.

Ok!
I tested the sensor on the bottom of the pump:
I pulled the connector and the arrow falled down, so....bad sensor?
Also this sensor is used by the Motronic to decide the mixture need?

That sensor is used only for the gauge and plays no part in the running of the bike.

Thanx Rick!

My 1223 error could come from this (bottom of the pump) sensor?

If the sensor behind the radiator works properly, the Motronic receves right informations and i shouldn't have problems with:
Too high engine temperature 
Fuel/air mixture 
Fan start/stop 

Correct?

Your 1223 code can not be from that sensor as it is not connected to the motronic unit in any way.
Even if the sensor behind the radiator is good you could still get a bad reading due to poor electrical connections which the motronic unit will read as low temperature and make the mixture rich. A poor connection will not make the fan turn on as it will only turn on if the resistance of the sensor is lower than normal.

well that may be right as a static measurement

but what happens when the engine is running wind passing and all that stuff

if the reference to the error code points to the temperature sender for the motronic ..sounds to me the motronic is seeing ..at some stage some very weird values ...perhaps there is some form of corrosion in the system , either at the sensor connections or in the loom as it reaches the motronic header plug ? or even the header plug connections to the computer ...

a mystery ? perhaps not ...when you find it ?

So i have to check the connectors and the wires. 

Sorry Charlie, i didn't understand your question: when you find it?

was just saying that I'm not familiar with the likely issues on a 16 valve model wiring loom and peripherals ...yet

but common experience has taught many of us that when there is a some form of connector involved ...and depending on your atmospheric conditions  the connector is the first place to look .

have you read about the many references about the product " deoxit "?

as I say, you will find it ..but it may take time ...

good luck

Thank you Charlie 

Today i will check!