# "Got invalid impossible slope calibration!" with G6 and xDrip+, can't calibrate...what to do?

**URL:** <https://forum.fudiabetes.org/t/got-invalid-impossible-slope-calibration-with-g6-and-xdrip-cant-calibrate-what-to-do/8622>\
**Category:** Tips, Tech & Gear\
**Tags:** xdrip\
**Created:** [November 6, 2019, 7:00am UTC](https://forum.fudiabetes.org/t/got-invalid-impossible-slope-calibration-with-g6-and-xdrip-cant-calibrate-what-to-do/8622 "2019-11-06T07:00:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Headlands](https://avatars.discourse-cdn.com/v4/letter/h/edb3f5/32.png) [@Headlands](https://forum.fudiabetes.org/u/Headlands)\
**Post date:** [November 6, 2019, 7:00am UTC](https://forum.fudiabetes.org/t/got-invalid-impossible-slope-calibration-with-g6-and-xdrip-cant-calibrate-what-to-do/8622/1 "2019-11-06T07:00:48Z")

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Hi all,

Just put in a new sensor and transmitter and this is the message when I try to calibrate it (it’s off by around 30 so it needs to be calibrated). I have OB1 and Native selected in settings, tried un-checking one at a time then both, with no luck.

I’ve seen some other posts in the past with this same issue, but no answers.

Any ideas?

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**Author:** ![MM2](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/mm2/32/3032_2.png) [@MM2](https://forum.fudiabetes.org/u/MM2)\
**Post date:** [November 6, 2019, 4:36pm UTC](https://forum.fudiabetes.org/t/got-invalid-impossible-slope-calibration-with-g6-and-xdrip-cant-calibrate-what-to-do/8622/2 "2019-11-06T16:36:38Z")

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This prior post may help.

> [@Can't calibrate xDrip+ anymore](https://forum.fudiabetes.org/t/cant-calibrate-xdrip-anymore/6198):
>
> Sorry for all the posts – I’m still getting used to xDrip and working through issues with it. Today I felt that the readings were off so I calibrated it with BG readings from my Freestyle Lite (the readings were indeed about 25 off), but got this message on xDrip+: “Sensor raw data sanity failure”, and nothing changed with the reading on xDrip. I tried it multiple times and also did the “override calibration” thing, which gave me the same result. I had to do the day before yesterday as well whe…

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<div class="post-metadata">

**Author:** ![MM2](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/mm2/32/3032_2.png) [@MM2](https://forum.fudiabetes.org/u/MM2)\
**Post date:** [December 26, 2019, 4:59am UTC](https://forum.fudiabetes.org/t/got-invalid-impossible-slope-calibration-with-g6-and-xdrip-cant-calibrate-what-to-do/8622/3 "2019-12-26T04:59:49Z")

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I just started a new G6 transmitter, (prior one was 81, new one 8G) and got similar message in xdrip (impossible calibration slope). I had to uncheck setting in debug for Fallback to xDrip, then it worked fine without error.