how to read car sensor signals?

Hello, I want to read DC signal with arduino. It is 2V 20ms per duration signal. But there is problem, in certain conditions can be 11,6v which would damage arduino's input pins. How to avoid that?

And this signal is PWM signal as far as i understand? how to read them correctly?

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Use a resistive voltage divider to reduce the sensor output voltage to be in the 0-5V range. 18K and 10K resistors would work.

I'd be looking at an optocoupler, but a voltage divider should do just fine as well. A voltage divider preserves the actual voltage levels, while an optocoupler turns it into a clean on/off signal.