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mike_a_mechanic, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 5471
Experience:  17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
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The car operates well when hot and running. Whe started from

Customer Question

The car operates well when hot and running. Whe started from cold or left for a few minutes after a run the throttle will operate as though I have my foot on the throttle
when the brakes are operated and automatic gears are changing down. Very frightening and dangerous.
Submitted: 3 years ago.
Category: Mercedes
Expert:  mike_a_mechanic replied 3 years ago.
Hello, welcome. My name is***** will do my very best to assist you with your question. I apologize if you have been waiting long for a response.

This issue comes from a failure to the turbine speed sensor which is located behind the valve body inside of the transmission. This is a common failure and requires the sensor to be replaced.
Customer: replied 3 years ago.
Is this sensor accessible when the outbox sump is off?
Expert:  mike_a_mechanic replied 3 years ago.
It is accessible with the valve body removed, which the gearbox pan has to be removed.
Customer: replied 3 years ago.
Is there a reason that this only seems to malfunction when cold? I would have thought that if the turbine speed sensor was faulty it would be malfunctioning all the time...this runs well most of the time only when cold it turns into "Christine" with the throttle being operated by what seems to be a heavy right foot.
Expert:  mike_a_mechanic replied 3 years ago.
This is common when the sensor is malfunctioning but not completely failed for the issue to only happen when cold. Thank you.
Customer: replied 3 years ago.
Can only rate on results. If your diagnosis proves correct and fixes the problem I will be very impressed. I thought I did rate you as very good a couple of days ago? This was for my experiences of your services and NOT results.
Expert:  mike_a_mechanic replied 3 years ago.
No my service has never been rated, you can continue to ask me further questions about this issue at anytime after rating positive otherwise the question will time out and close. Thank you.