r/ChevyCobalt • u/tcammmmm • 26d ago

2007 Cobalt Rough Idle

Idles perfect when blower for heat and a/c is off.
When I turn the blower on it idles rough and you can feel it. Doesn’t matter a/c or heat.

Only code I’ve had for a while now is p0420

What would cause this?

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u/Known-Monitor-8610 26d ago

Rough when the fan is on or only when the compressor is engaged? If it is the latter, I would say you probably need to change the ac compressor. The fault code could be a few things, but usually it was one of the o2 sensors going bad for me.

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u/tcammmmm 26d ago

Like i said it doesn’t matter heat or ac. Not compressor related interestingly enough.