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When car is hot it will not always start,,let it cool off…

Customer Question
When car is hot...

When car is hot it will not always start,,let it cool off and it will then start

Mechanic's Assistant: Have you checked the battery, particularly the terminal connections? Are they corroded?

I have checked battery it is not corroded.

Mechanic's Assistant: What is the model/year of your Mercedes?

2002 s430

Mechanic's Assistant: Are you fixing your S430 yourself? What have you tried so far?

I want to fix my self but, may have to take to shop. i have not tried anything

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Yes, in winter key will not turn imediately, must wait five minuets or more.

Submitted: 10 months ago.Category: Mercedes
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Answered in 7 minutes by:
10/5/2017
Mercedes Mechanic: Pete, Mercedes Mechanic replied 10 months ago
Pete
Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 33,359
Experience: Over 15 years experience as a Mercedes dealer technician
Verified

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

It sounds like you have 2 issues here.First and the most common cause for the no start when hot is the crank sensor.The crank sensor detects pulses from the crank/flywheel to help the computer and ignition components operate.It tends to weaken over time and when the engine heats up it fails to send a signal causing this fault here.This sensor is located at the back of the cylinder head on the drivers side mounted near the bottom of the head where the transmission bolts up.The sensor itself is usually around $100 at a dealer or local parts store and about an hours labor to have replaced.This was a very common sensor to fail and causes this exact fault here as I have seen and had to replace numerous times on Mercedes vehicles with the 112 and 113 engines ( yours is a 113 engine).The signal from the crank sensor can be checked on a compatible scan tool plugged into your vehicles data port observing the engine rpm signal.If there is 0 rpm signal on the scan tools data list when cranking it over when it does not start then this sensor needs replaced.

As for the key not turning immediately in the winter first make sure the batteries are o.k. in the remote.If they are weak they need replaced.A local battery store can test them for you.If these are o.k. then I suspect the electronic ignition switch is causing a bind when colder in the winter causing the delay or having to jiggle the key.I have seen the ignition switch fail like this before in several cases with it needing replaced.I would have this checked ( you may have to wait until it starts to act up) to see if it needs replaced as this is when it is best tested.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated ( should be a link to click on here or above).You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

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