RPM needle moves up and down while I'm stopped at a red light.
Why does my 2008 Cobalt RPM needle move up to 20 then 30 and back down. This happened while I was stopped at a red light with my foot on the brake. After the light turned green, the car felt jerky as I went to drive.
Does your engine also race up and down? If so, it is not the tachometer. Are you getting any check engine lights? You may have a sensor going out, either in the air sensor or smog sensing units giving false readings to your computer. Have a shop hook you up to a computer reading machine and see what they pick up.
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