I have a slk 98 comp mercedes, it has a engine problem.

Sounds like a vacumn leak...do not adjust the idle...this is a symptom of a vacumn leak...or solenoid...

how do you get to the horn
on mercedes 230slk

Bring it back to Mercedes and get the sensitivity adjusted, it needs to be lowered.

Could be mechanical, fluid or electronic problem.

Fault will be indentified with a diagnostic scanner. Check for shop with a Star or Launch scanner.
If they don't understand your request...run away !

Being as it happens warm, I would think it is a bad forward clutch drum seal allowing fluid pressure to drop below operating pressure. If so, trans' will need repair.

Check here for shop in your area ....http://www.iatn.net/shopfinder/

...........or see your friendly Mercedes dealership service department.

Located in the Fuel Tank

the codes are read with an OBD 2 code reader or scanner through the data link connector in front of the driver under the dash, it is a 16 pin connector. U can buy a code reader on ebay for around $35

You can see the belt layout for SLK 350 on page 61 of the pdf:
http://www.billsden.org/fileadmin/media/mercedes/slk/docs/train_slk_r171_intro.pdf

Check one of the fuses in the bonnet. There is most likely an electrical contact problem. You will need a fuse wire replacement

send your car to authorize dealer to scan the fault,avoiding guessing of replacement of part,ty

Hi it is possible on your car that it will have a obd2 socket but will not be obd2. What are you useing to try to read the fault codes?
As far as the fault goes have you tried a new MAF?