# Bad mileage

**URL:** <https://community.cartalk.com/t/bad-mileage/79706>\
**Category:** Maintenance/Repairs\
**Created:** [June 3, 2013, 3:26am UTC](https://community.cartalk.com/t/bad-mileage/79706 "2013-06-03T03:26:17Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![joatmon](https://avatars.discourse-cdn.com/v4/letter/j/7ea924/32.png) [@joatmon](https://community.cartalk.com/u/joatmon)\
**Post date:** [June 3, 2013, 3:26am UTC](https://community.cartalk.com/t/bad-mileage/79706/1 "2013-06-03T03:26:17Z")

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I get bad mileage. The check engine lights not on and it passed a scan… so o2 sensors arr good…sometimesit has a low idle so should I get the fuel pressure checked…I’m thinking filter but its in the tank with the pump…I am in the process of using sea foam to help clean the injectors???

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**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\
**Post date:** [June 3, 2013, 3:32am UTC](https://community.cartalk.com/t/bad-mileage/79706/2 "2013-06-03T03:32:31Z")

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Year, make, model, mileage? And, what do you mean by ‘bad gas mileage’? Change the spark plugs recently?

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**Author:** ![joatmon](https://avatars.discourse-cdn.com/v4/letter/j/7ea924/32.png) [@joatmon](https://community.cartalk.com/u/joatmon)\
**Post date:** [June 3, 2013, 4:32am UTC](https://community.cartalk.com/t/bad-mileage/79706/3 "2013-06-03T04:32:08Z")

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05 grand prix 3.8 v6 no supercharger… 11 miles per gallon…I plan on sparkplugs tune up etc…as I just bought it

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**Author:** ![joatmon](https://avatars.discourse-cdn.com/v4/letter/j/7ea924/32.png) [@joatmon](https://community.cartalk.com/u/joatmon)\
**Post date:** [June 3, 2013, 4:32am UTC](https://community.cartalk.com/t/bad-mileage/79706/4 "2013-06-03T04:32:48Z")

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128 k miles…

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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:** [June 3, 2013, 4:47am UTC](https://community.cartalk.com/t/bad-mileage/79706/5 "2013-06-03T04:47:17Z")

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If you just bought the vehicle you might try replacing the thermostat.

If the thermostat is stuck open the coolant doesn’t get to the proper temperature and the engine uses more fuel.

Tester