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Q:

rpms go up and down when idleing on 2004 Pontiac Grand Prix

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
cars rpms go up and down when idleing. car has new cats and o2 sensors and check engine light is not showing anything is wrong?
(2) Answers
I had the same problem with my car start about 2 months ago and thought it was the O2 sensor as well, but it turns out it was the mass flow air sensor instead.
The cause of an idle surge can sometimes be hard to pinpoint. A sensor could be failing but not enough to turn the check engine light on. You may have a dirty throttle body or a fuel injector issue. This problem may need to be checked out by a qualified technician. If you don't have a regular shop that does your repairs check out the listings at www.repairpal.com.