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Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience:  Tech Expert
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Hello! Have 2000 s500L. 85000 miles. Has suddenly lost power

Customer Question

Hello! Have 2000 s500L. 85000 miles.
Has suddenly lost power when going up hills. Felt like the car was running out of petrol or had dirt in the petrol.
When almost stopped, it would speed up to about 20 mph but no more until hill flattened out.
Car then gradually speeded up to normal (60 - 70).
Let the car slow to 40 and tried kick down -no response - in fact it seemed again that the engine wasn't getting petrol.
Any ideas.
Submitted: 4 years ago.
Category: Mercedes
Expert:  Mike replied 4 years ago.
Hello and Welcome to justanswer..

My name is MIKE, Im happy to help you with this..

Im sorry to see you have had a wait on your question -

Can you please tell me exactly what you have done / had done by way of tests / checks etc so far/ since asking your question?

Plus - when this occurred - did you get any fault lights / messages on the dash?

Rgds, MIKE......................................
Customer: replied 4 years ago.

Dear Mike,

No flashing lights on dashboard. Car has been parked since problem.

When idling at 500 rpm engine gave an occasional 'miss'.


Expert:  Mike replied 4 years ago.
Hello again John..

Thank you for your reply - sorry I missed it late last eve.

It sounds as though its lost its throttle control John - but there are other things too.

These have what's called a TPS - Throttle position sensor - you need to check the wiring to that - but if faulty ,the TPS needs to be replaced. Check also at the throttle body - the wiring etc to that .

Ideally John you should have a plug in diagnostic test done to clarify this before buying any parts and I would suggest that be done.

Meantime, check just in case that there are no restrictions developed in the air tubing to the engine from the filter. It has been known where the air filter breaks up , goes up the tubing and strangles the air supply.

Similarly, the fuel filter - if its more than 10k miles / 10-12 months old, that could have developed a restriction starving the engine of fuel - so renew that if suspect as above.

Too - it could have developed a fuel supply / pump issue - if needs be the pressure needs to be checked. If its starved of air or fuel as above, you will get these symptoms too - so it all needs checking.

I don't know if you have access to a plug in diagnostic fault reader machine ( some do ) It plugs in the circular diag socket under the bonnet- that will check the TPS /circuit for you -and of course will highlight any other faults / things going on.

I also don't know if you can do any of the above yourself or not- but if not ( inc the diag tests ) - I would suggest as its pretty much un driveable it seems - contact and use a good local mobile mechanic - who should have the equipment needed to get this checked through as above and sorted for you .
Thats the way forward on this one now John.

Let me know if you need anything more on this at all -

Meantime -- Please click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.