How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Marty Your Own Question
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53904
Experience:  Bosch Certified Master Tech. Over 35 years experience.
Type Your Mercedes Question Here...
Marty is online now
A new question is answered every 9 seconds

I have a 1999 SLK R170 230. I have a problem where the car

Customer Question

Hello, I have a 1999 SLK R170 230. I have a problem where the car will not start (or even will not turn over), the Fan comes on straight away as well. I followed a few forums who advised to check the K40 module as this can develop faults. The K40 Module was changed, as well as a brand new battery being installed. This appeared to solve the issue and the engine started..... within 10 minutes though the engine cut out and no will not even turn over again, and the Fan starts up each time the ignition is turned on.
Can you please advise.....
Thank you
Karl :)
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi Karl, my name is***** sounds like you received a defective K40 relay. Did you install a new or a used relay? I'd return the relay and exchange it for another. The fan coming on when you turn the key on is a telltale sign of a bad K40 relay. I'd also check all of the connectors that plug into the relay and make sure they are clean and tight.

Let me know if you have any questions.


Expert:  Marty replied 1 year ago.

Hi Karl, I'm just following up with you on the Mercedes. Did you ever get this repaired?

Customer: replied 1 year ago.
Hello Marty,
Not sure why you have not received my earlier reply....??
I changed the K40 3 times without any change, I then changed the ignition switch.... again no results.
After some investigation, I discovered that there are in fact 2 different K40 modules, even though they look identicle. Both are listed for the R170 230. I tried yet another K40 and it started straight away.
The only fault now is that I am unable to rev the engine, it ticks over lovely, but the minute the accelerator is pressed, the engine splutters and tries to die. I have changed all the filters, fuel filters, oil filters and air & cabin filters. Installed new plugs and changed the oil....... still does like to rev above idle. (I have filled her with fresh fuel as well). Any ideas ???
Expert:  Marty replied 1 year ago.

Hi Karl, glad you got it going with the correct K40 relay. Try turning the key to the on position without starting the car and leave it on for about 3 minutes then start the car and see if the throttle responds.

Let me know if it works. Please don't forget to click on a rating for my service as this is the only way I receive credit from the website for helping you.


Expert:  Marty replied 1 year ago.

Hi Karl, just checking in. Did you try the reset procedure for the throttle actuator that I sent you?

Related Mercedes Questions