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Q: Starter, alternator, or battery?

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Car died the other day mechanic said my cars alternator was running 12.5 volts instead of the 15 it is supposed to run but it should be fine for a while. I turned my car off later the night and it would not turn back on the next morning, my neighbor jumped it again and it stayed on but once again after turning off it wouldn't start Could it be that I killed my battery completely or is it my alternator.
My car's transmission is unknown to me.

Hi there. In most cases, when you’re pulling less than 15 volts from the alternator the issue is caused by an internal component failure within the alternator itself or the alternator relay. If the starter is not receiving the correct amps, it’s the battery that is at fault. With this type of situation, the best recommendation is to have a professional mechanic complete a no start inspection first. From there, they can determine if your VW issues are caused by the alternator, battery, or the starter. It may be a combination of two that need to be replaced - especially if the battery has not been replaced in the last few years.

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