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Stan
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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I have a Mercedes 500 SL 2003. I keep getting the message "

Customer Question

I have a Mercedes 500 SL 2003. I keep getting the message " Coolant level, Visit workshop". However, when I check the coolant level, the Level is FINE and no Leaks have been observed visually.
I took the Car to a Garage, they did a "pressure test" and could NOT find any leaks.!! The message keeps coming on and off and some times the Temprature gauge reaches 120 and then drops!!
The Wind screen fluid reservoir is leaking, however it holds enough fluid the screen. I have heard the Sensor circuit system (Radiator) and wind screen fluid reservoir/container is connected in series and may be this is the reason the "warning Light" "Visit Workshop" comes on.!!
Please advise
Submitted: 2 years ago.
Category: Mercedes
Expert:  Stan replied 2 years ago.
Stan :

,
When coolant and windsreen fluid level is in order, the respective switch has 0 ohms. If the switch has a different resistance when levels are in order- this switch is faulty.
Another possiblity error message is failed fan module. Normally, when coolant temperature is above 100 degrees Celsius, the fan must run at full speed. If this does not happen- engine control unit fault codes and fan actuation should be checked. Most likely the fan module is faulty, and causes the coolant temperature to go up.

Stan :

best regards,
Stan

JACUSTOMER-05c3au1h- :

Can you please advise how the "Fan Module " is be checked. Will the Computer connected the faults SHOW the fault code? .

JACUSTOMER-05c3au1h- :

Can you please advise how the "Fan Module " is be checked. Will the Computer connected the faults SHOW the fault code?

JACUSTOMER-05c3au1h- :

1-Can you please advise how the "Fan Module " is be checked. Will the Computer connected the faults SHOW the fault code?

JACUSTOMER-05c3au1h- :

-Can you please advise how the "Fan Module " is be checked. Will the Computer connected the faults SHOW the fault code?

Stan :

,
Mercedes-Benz specific Star Diagnosis computer will show the fault code and allow to actuate the fan to test it. Some independent MB workshops have the Star Diagnosis besides authorized dealers.

JACUSTOMER-05c3au1h- :

Dear Stan, Thanks. Therefore from what I have understood from your comment above, the Wind Screen Fluid reservoir in my car having a leak HAS NO THING TO DO with the warning message " Coolant", Visit workshop. Can you please confirm. Thanks

Stan :

If it leaks slowly, then the level will be ok least some time. If fluid level sensor is in order- it will not cause the coolant error message.
If the windshield fluid sensor has failed, in theory it can cause coolant error message.