# IAC Valve Symptoms

**URL:** <https://community.cartalk.com/t/iac-valve-symptoms/182252>\
**Category:** Maintenance/Repairs\
**Tags:** buick, century\
**Created:** [February 2, 2022, 3:38pm UTC](https://community.cartalk.com/t/iac-valve-symptoms/182252 "2022-02-02T15:38:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jmcarc](https://avatars.discourse-cdn.com/v4/letter/j/278dde/32.png) [@jmcarc](https://community.cartalk.com/u/jmcarc)\
**Post date:** [February 2, 2022, 3:38pm UTC](https://community.cartalk.com/t/iac-valve-symptoms/182252/1 "2022-02-02T15:38:34Z")

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Last year, I replaced my Idle Air Control valve because of stalling while idling. Could a defective IAC valve also cause excessively fast idle? Or, do I have to look elsewhere for the problem?

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**Author:** ![NYBo](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nybo/32/17281_2.png) [@NYBo](https://community.cartalk.com/u/NYBo)\
**Post date:** [February 2, 2022, 3:41pm UTC](https://community.cartalk.com/t/iac-valve-symptoms/182252/2 "2022-02-02T15:41:50Z")

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It could, but I would start by looking for vacuum leaks.

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [February 2, 2022, 3:44pm UTC](https://community.cartalk.com/t/iac-valve-symptoms/182252/3 "2022-02-02T15:44:00Z")

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Try rapping on the IAC valve with the handle of a screwdriver while the engine is idling.

If the idle speed changes, the IAC valve is faulty.

Tester