# Check engine light will not go off

**URL:** <https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380>\
**Category:** Maintenance/Repairs\
**Tags:** chevrolet, tahoe\
**Created:** [February 13, 2010, 3:30pm UTC](https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380 "2010-02-13T15:30:50Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Chuck9999](https://avatars.discourse-cdn.com/v4/letter/c/ba9def/32.png) [@Chuck9999](https://community.cartalk.com/u/Chuck9999)\
**Post date:** [February 13, 2010, 3:30pm UTC](https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380/1 "2010-02-13T15:30:50Z")

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I had the code read by Auto Zone 3 times as well as had them turn it off 3 times after replacing the o2 sensor. I took it back to the shop where it was replaced to show them the diagram of which sensor it was. They had replaced the right sensor. The premium gas with no ethanol has not helped either. It still reads as the same o2 sensor is not working.

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**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\
**Post date:** [February 13, 2010, 3:53pm UTC](https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380/2 "2010-02-13T15:53:21Z")

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The check-engine light doesn’t necessarily mean the sensor is bad. It means the output of the sensor is out of range. This could be because the sensor is accurately telling you that the thing it’s monitoring is malfunctioning.

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**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\
**Post date:** [February 13, 2010, 4:28pm UTC](https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380/3 "2010-02-13T16:28:53Z")

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Get the code, such as P0444, and bring it here for advice. The cause of the code might be wiring, or voltage supply.

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**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\
**Post date:** [February 13, 2010, 4:37pm UTC](https://community.cartalk.com/t/check-engine-light-will-not-go-off/44380/4 "2010-02-13T16:37:12Z")

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The codes don’t tell you that an O2 sensor isn’t working. You have, in fact, now take the most expensive route to finding the problem. Since you have replaced the O2 sensor and still have a problem you now know (for fairly certain) that you sensor was just fine. As noted, get and post the actual code (e.g. P0171).

What year is the Tahoe?