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Q: Won't start after it runs for a few minutes until I let it set for hours.

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Won't start after it runs for awhile. Have to let it set for hours.

My car has 100000 miles.
My car has an automatic transmission.

A: Hello - if the Check Engine light is on, ge...

Hello - if the Check Engine light is on, getting the problem codes is the first task. Check also battery and ground cable connections for corrosion or loose connectors. Determining whether you are missing spark or fuel during these "hot start" attempts is the next level of diagnosis. Lack of spark could be a coil or ignition module failure. Lack of fuel or fuel pressure could be the fuel pump, fuel pump relay, or the fuel pressure regulator. I would recommend a inspection of the engine during one of these "no hot start" episodes

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A: This is a common sign of a faulty ignition ...

This is a common sign of a faulty ignition coil. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil's ability to function. This type of temperature cycling happens because every time you shut the engine off, the fan stops running, the coolant stops flowing and the temperature under the hood rises. Every time you start the engine again the coolant flows, the fans turn on, and the temperature drops. When this heat dissipates and is absorbed under the hood, it is trapped causing this cycling effect. Components that contain heat sensitive materials include parts like coils, injectors, igniters, and some sensors. Any of these may be potentially subject to this same kind of heat problem which can be very difficult to trace. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to properly diagnose your ignition system.

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