water warning light on SLK230

[mlc]

The yellow radiator warning light has started to come on occasionally on our 2003 SLK230. This has started in the last couple of weeks and has happended about 5 -6 times. the light only stays on for a couple of minutes then goes off. The water level is fine and has never needed topping up. The handbook says that if this happens and the water level is ok then (if the car has Air Con) then the fan isnt working correctly.

The car does have air con, but as the weather in Manchetser is currently fairly cold and the problem is nearly always in rush hour motorway traffic - ie 30 - 50mph and therefore not when I would expect the engine to be getting too warm. The temperature gauge is hovering at its normal half way position.

Anyone got any ideas?

Thanks in advance.

mark.

 

[Ellsy Tanners]

Check your washer level, this can confuse the car a put on the coolant light on in error.
The two sensors are wiried in series and this can some times cause errors.

Also push down the floating valve in the coolant header tank when topping up, this allows the full mlevel to be reached. If your car is a 170 that is.

 

[mlc]

Thanks for that, I have now checked the screen wash as well. Any one know how to check that the fan is working ok?

 

[panason1c]

The yellow radiator warning light has started to come on occasionally on our 2003 SLK230. This has started in the last couple of weeks and has happended about 5 -6 times. the light only stays on for a couple of minutes then goes off. The water level is fine and has never needed topping up. The handbook says that if this happens and the water level is ok then (if the car has Air Con) then the fan isnt working correctly.

The car does have air con, but as the weather in Manchetser is currently fairly cold and the problem is nearly always in rush hour motorway traffic - ie 30 - 50mph and therefore not when I would expect the engine to be getting too warm. The temperature gauge is hovering at its normal half way position.

Anyone got any ideas?

Thanks in advance.


mark.

My 2002 ML did exactly the same thing....at first it randomly stayed on for a couple of minutes at a time but eventually it began to stay on for longer periods..it turned out to be the fan control unit which is supplied as a complete unit including the electric fan.....not cheap!!

During the periods the light was on i noticed that the fan was stationary when it should not have been.

 

[panason1c]

If your fan control unit is the same as mine (see picture) then check the fuse block that is located on the + battery pole (see picture), this fuse is for the fan control unit..............


Edit.........On second thoughts, when this fuse blows - the coolant light would stay on all the time....so not the fuse then!

 

[moosehead]

Had the same probelm with the wife's SLK. Turned out to be the coolant level sensor in the header tank. Dead easy to replace with no need to drain the system. I think it was around a tenner from Eurocarparts.