With nothing on the GPIO pins (including no fan shim) the I2C works normal. sudo i2cdetect -y 1 completes all addresses near instantly. Mount the Fan Shim, mechanical only - no software: I2C fails. sudo i2cdetect -y 1 takes over a second per address How to prevent the Fan Shim from interfering…

Fan Shim blocks I2C

PiTinker November 10, 2019, 6:44pm 2

I considered making a dumb shim, but pins 3 & 5 are not so easily circumvented

Topic		Replies	Views
Fanshim Support	14	981	September 14, 2019
Questions about GPIO pins used on Fan Shim Support	10	2784	December 30, 2020
Fan Shim button always held Support	10	2215	July 5, 2019
Fan shim & button shim together? Support	3	763	January 4, 2020
Making fan shim "dumb" Support	19	3561	December 10, 2019