Q: Car stalls while driving on high way.

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While im driving on the highway my car dies, it seems to die after i have drove 20 miles at highway speeds and after the 20 miles it usually dies I get over a hill and start going down a hill the RPMS just drop to zero and all my gauges turn on and i pull over and try to start it and it wont start up right away it usually takes 5 minutes to start. I will continue to drive home and it will die in 2-5 miles instead of the 20.

My car has 148000 miles.
My car has an automatic transmission.

Hi there. Check the oil pressure that the engine is producing. At highway speeds, if the engine is stalling out, then the oil pressure could drop to under 12 psi. The computer will sense this pressure drop and shut down the electronics to stop the engine. If you have not changed the engine oil in 3000 or less, then I recommend changing the engine oil and see if the symptom continues. If the symptoms continue, then check the computer specs while driving on the road at highway speeds. If the speedometer reads the speed limit, but the computer reads higher than that, then the communication from the computer to the speed sensor has failed. Check the speed sensor on the output shaft and see if there is any metal debris on the magnet. This will disrupt the transmitting voltage and change the speed ratings in the computer. If you need further assistance with your engine stalling at highway speeds, then seek out a professional, such as one from Your Mechanic, to help you.

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