# Audi A4 - losing coolant rapidly but no leak?

**URL:** <https://community.cartalk.com/t/audi-a4-losing-coolant-rapidly-but-no-leak/63182>\
**Category:** Maintenance/Repairs\
**Tags:** audi, a4, coolant\
**Created:** [March 30, 2011, 7:55pm UTC](https://community.cartalk.com/t/audi-a4-losing-coolant-rapidly-but-no-leak/63182 "2011-03-30T19:55:48Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\
**Post date:** [March 31, 2011, 4:00pm UTC](https://community.cartalk.com/t/audi-a4-losing-coolant-rapidly-but-no-leak/63182/6 "2011-03-31T16:00:00Z")

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Not the temperaure sensor, the termostat, which is a valve that opens when the engine warms up to allow coolant to circulate through the radiator. If the thermostat is defective it will prevent coolant circulation and thereby cause the engine to overheat.

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