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Ask Lou P. master tech Your Own Question
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4961
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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1995 Mercedes S420... When car reaches operating temp it

Customer Question

1995 Mercedes S420... When car reaches operating temp it will not restart... Car must cool in order for it to start. Already changed Crank Sensor. Any idea what else could cause this problem.
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.

Hello, does the engine die when warm?

Customer: replied 1 year ago.
Before we replaced the crank position sensor the car would die when it reached operating temp. Now that the crank postion sensor was replaced the car stays running but will not restart once warm.
Expert:  Lou P. master tech replied 1 year ago.

ok,where did you get the new sensor from?

Customer: replied 1 year ago.
From WorldPac...
Customer: replied 1 year ago.
Its an aftermarket crankpostion sensor made by Original Equipment
Expert:  Lou P. master tech replied 1 year ago.

ok, world pac sensors have issues sometimes, here is what i would do, ohm the new sensor when cold and let it warm up and shut the car off, when it does not restart re ohm the sensor and compare they should be near identical or within 100 ohms, not thousands or open. unless you have a scan tool to read rpm?

Customer: replied 1 year ago.
Ok I have a scan tool or ohm meter which do you recommend?
Expert:  Lou P. master tech replied 1 year ago.

ok sweet, does your scan tool show rpm data when engine running or cranking?

Customer: replied 1 year ago.
it is an autoland scanner... complete MB functions. I can read live data
Expert:  Lou P. master tech replied 1 year ago.

PERFECT so what the rpms , get the car hot and shut it off, if it does not start then access the rpm data and see if it recognizes rpm as the engine is cranking

Customer: replied 1 year ago.
ok still having this problem and now the car is idling high and low...
Expert:  Lou P. master tech replied 1 year ago.

OK i will opt out hopefully another expert can assist better, please do not reply until another expert replies or it will lock you back to me.