W209 CLK55 2004 ongoing major problem (Coolant Visit Workshop)

[financenick]

Hi,

I have the dreaded "Coolant Visit Workshop" warning permanently on my dashboard, and the radiator fan is on full blast. Now ive seen some threads around that have tried tackling this problem, but wanted to start another, as the one's ive read all seem rather vague ref the cure.

1) Some say the fan module is broken (not in my case as ive tried 2 other fans and still did the same thing)

2) Some say its a relay in the front SAM unit (checked swapped replaced all mine and still same problem)

3) Some say its the expansion tank sensor, but this would not bring on the fan full blast

4) Some say its the cars ECU, this i would have checked but cant even find it - DOES ANYONE KNOW WHERE THIS IS LOCATED?

If anyone has any proper knowledge of this issue feel free to comment. The fault codes that came up on the diagnostics were P1999 & P2083

 

[V12]

I had this problem on my 2003 clk. It may or may not be identical to yours but I bought a new sensor as that was cheap as chips anyway. Went to fit it and noticed the cable and plug weren't in good nick with lots of corrosion. Went to clean it and one of the wires snapped off the plug so easily.
I cut it back 4" and the copper was still greeny black, so cut it back another few inches and again until clean copper and then joined a new section in.

Problem solved for me.

 

[financenick]

have a funny feeling this prob confined to CLK55's on 2004 year, so quite rare

 

[jaymanek]

The couple of times we have had this its been the front SAM... Best to get it to someone with a Star machine.

 

[financenick]

The couple of times we have had this its been the front SAM... Best to get it to someone with a Star machine.

Will the star machine confirm this (is that what you mean?)

 

[financenick]

anyone else experienced this prob before?

 

[BlackC55]

Yes. Many times.

It could be the SAM, engine control unit, poor wiring to the fan itself, a faulty AC control unit etc.

The Star won't pinpoint the fault but it will help. You may also need wiring diagrams too to do a proper check.

 

[steveatpipex]

Did you get this sorted? I have the same problem, other threads have suggested May also be a defective wire between the fan and the ecu.
Be interested to see how it went for you cheers

 

[financenick]

its at a Mercedes specialist as we speak, and has been there for a week now, and no one car sort the problem, im getting worried now

 

[WG M-B]

Where are you based????

 

[financenick]

dartford

 

[The _Don]

dartford

Who has the car?

 

[financenick]

a Mercedes specialist in bexley

 

[steveatpipex]

Hi have you had a result yet please?

 

[BlackC55]

Have you had all the items I have suggested looked at?

 

[financenick]

Yep, ok so the result is front Sam and wiring been checked, and no faults, so last thing it can be is ecu fault

 

[steveatpipex]

Hi BlackC55 not sure if that was meant for me or the OP. I still get the coolant visit workshop message. I've checked the fuse 51, the plug and cable going into the fan control unit at the bottom of the radiator, I've checked the resistance on the coolant temperature sensor to make sure it changes as the engine heats up, I've visually checked the cable I can see, and visually looked at the SAM and nothing stands out. I also had a leak repaired in the Air Con system and regassing which is now blowing like an article wind.
With mine, the fan starts up and goes into high mode constantly until a few seconds after switching off the engine, which I understand is its safe mode. I don't know how to check the ECU ( or even where it is!) so I'm beginning to think I need to visit an Indy to help sort it. Verbally one has told me it's probably the fan control unit, but needs confirming. If you can suggest anything else I can do on my drive first I'd be grateful!

Edited to add mine first appeared when it was off road SORN, it was fine when I laid it up. Sorry cross posted with Op too.

 

[BlackC55]

Your next port of call is a plug into a star.

 

[6cyl]

Any updates on this Nick / Steve?

 

[financenick]

Hi BlackC55 not sure if that was meant for me or the OP. I still get the coolant visit workshop message. I've checked the fuse 51, the plug and cable going into the fan control unit at the bottom of the radiator, I've checked the resistance on the coolant temperature sensor to make sure it changes as the engine heats up, I've visually checked the cable I can see, and visually looked at the SAM and nothing stands out. I also had a leak repaired in the Air Con system and regassing which is now blowing like an article wind.
With mine, the fan starts up and goes into high mode constantly until a few seconds after switching off the engine, which I understand is its safe mode. I don't know how to check the ECU ( or even where it is!) so I'm beginning to think I need to visit an Indy to help sort it. Verbally one has told me it's probably the fan control unit, but needs confirming. If you can suggest anything else I can do on my drive first I'd be grateful!

Edited to add mine first appeared when it was off road SORN, it was fine when I laid it up. Sorry cross posted with Op too.

ive now fixed this problem, was the ECU needed fixing, and adapter wire fitted - job done