# 2014 Cadillac ATS - Mystery noise

**URL:** <https://community.cartalk.com/t/2014-cadillac-ats-mystery-noise/144069>\
**Category:** Maintenance/Repairs\
**Tags:** cadillac\
**Created:** [July 10, 2019, 11:44am UTC](https://community.cartalk.com/t/2014-cadillac-ats-mystery-noise/144069 "2019-07-10T11:44:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Thale](https://avatars.discourse-cdn.com/v4/letter/t/9dc877/32.png) [@Thale](https://community.cartalk.com/u/Thale)\
**Post date:** [July 10, 2019, 11:44am UTC](https://community.cartalk.com/t/2014-cadillac-ats-mystery-noise/144069/1 "2019-07-10T11:44:49Z")

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when starting my car its this loud annoying humming noise?sound that goes away …about 30 Seconds or so it goes away…sometimes while driving it happens as well

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**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\
**Post date:** [July 10, 2019, 12:23pm UTC](https://community.cartalk.com/t/2014-cadillac-ats-mystery-noise/144069/2 "2019-07-10T12:23:03Z")

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Could be the smog pump. California ATS have an electric smog pump.

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**Author:** ![tcmichnorth](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tcmichnorth/32/25126_2.png) [@tcmichnorth](https://community.cartalk.com/u/tcmichnorth)\
**Post date:** [July 10, 2019, 1:16pm UTC](https://community.cartalk.com/t/2014-cadillac-ats-mystery-noise/144069/3 "2019-07-10T13:16:47Z")

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Do these still have air shocks with a pump? If so, it could be a leak in the air shock system and pump is turning on to compensate