# Help with an i2c issue Sensor Init failed -\>Error: EACCES: permission denied, open '/dev/i2c-1'
**URL:** https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610
**Category:** Troubleshooting
**Created:** [21 November 2019 22:17 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610 "2019-11-21T22:17:09Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@NastySpill](https://dietpi.com/forum/u/NastySpill)
#### Post date: [21 November 2019 22:17 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610/1 "2019-11-21T22:17:09Z")
Hi All,
I’m a newbie in Dietpi and the linux environment. I am persisting through a few configuration issues to learn this world as its blown me away with the possibilities and level of development.
So… I am trying to get a BME280 sensor working in Node-Red on Raspi W Zero. But have what appears to be a user permission error in node red debug terminal;
```nohighlight
'Sensor Init failed ->Error: EACCES: permission denied, open '/dev/i2c-1'
```
The reason I am posting in the Dietpi forum is that I had this exact issue;
[https://www.raspberrypi.org/forums/viewtopic.php?t=228084](https://www.raspberrypi.org/forums/viewtopic.php?t=228084) which may be a bug in the Dietpi…??
And now my i2c device appears on bus 1 0x077 when viewed with i2ctools.
```nohighlight
root@DietPi:~# root@DietPi:~# i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- 77
root@DietPi:~#
```
But after numerous restarts I still get this error in node red.
```nohighlight
'Sensor Init failed ->Error: EACCES: permission denied, open '/dev/i2c-1'
```
I have read through a few forums that have got me very close but I think my issue is a permission… [The node’s page](https://www.npmjs.com/package/node-red-contrib-bme280) suggests I look at [this page](https://github.com/fivdi/i2c-bus) to configure i2c access, but I can’t see any information, at least it’s not near the surface…
This is the contents of my rules file;
(sudo nano /lib/udev/rules.d/60-i2c-tools.rules)
```nohighlight
SUBSYSTEM=="i2c-dev",
KERNEL=='i2c-0" , GROUP="i2c", MODE='0666"
KERNEL=='i2c-[1-9]*" , GROUP="i2c", MODE='0666"
```
Is 666 even correct?
I’m unsure where to look next. Any ideas would be appreciated.
---
### Author:  [@NastySpill](https://dietpi.com/forum/u/NastySpill)
#### Post date: [21 November 2019 22:21 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610/2 "2019-11-21T22:21:45Z")
```nohighlight
ls -l /dev/i2c*
```
returns
```nohighlight
root@DietPi:~# ls -l /dev/i2c*
crw-rw---- 1 root i2c 89, 1 Nov 21 06:00 /dev/i2c-1
```
Which seems correct to me…
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [22 November 2019 16:33 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610/3 "2019-11-22T16:33:05Z")
NastySpill
Please check: cat /etc/udev/rules.d/99-com.rules
It should contain: SUBSYSTEM==“i2c-dev”, GROUP=“i2c”, MODE=“0660”
This means all members of group i2c have full R/W access to the I2C devices.
Hence: usermod -aG i2c nodered
Since Node-RED is commonly used for this, I’ll add this step to our install script.
---
### Author:  [@MichaIng](https://dietpi.com/forum/u/MichaIng)
#### Post date: [22 November 2019 17:08 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610/4 "2019-11-22T17:08:13Z")
Done: [https://github.com/MichaIng/DietPi/commit/6460c27ba51a42b5d71ebaae4c7291184cf777b7](https://github.com/MichaIng/DietPi/commit/6460c27ba51a42b5d71ebaae4c7291184cf777b7)
Changelog: [https://github.com/MichaIng/DietPi/commit/3918b9713f4cddfccd5ea179f9934f58c545154f](https://github.com/MichaIng/DietPi/commit/3918b9713f4cddfccd5ea179f9934f58c545154f)
---
### Author:  [@NastySpill](https://dietpi.com/forum/u/NastySpill)
#### Post date: [25 November 2019 03:32 UTC](https://dietpi.com/forum/t/help-with-an-i2c-issue-sensor-init-failed-error-eacces-permission-denied-open-dev-i2c-1/3610/5 "2019-11-25T03:32:07Z")
Yes that line is present;
```nohighlight
root@DietPi:~# cat /etc/udev/rules.d/99-com.rules
SUBSYSTEM=="input", GROUP="input", MODE="0660"
SUBSYSTEM=="i2c-dev", GROUP="i2c", MODE="0660"
SUBSYSTEM=="spidev", GROUP="spi", MODE="0660"
SUBSYSTEM=="bcm2835-gpiomem", GROUP="gpio", MODE="0660"
SUBSYSTEM=="argon-*", GROUP="video", MODE="0660"
SUBSYSTEM=="rpivid-*", GROUP="video", MODE="0660"
SUBSYSTEM=="gpio", GROUP="gpio", MODE="0660"
SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c '\
chown -R root:gpio /sys/class/gpio && chmod -R 770 /sys/class/gpio;\
chown -R root:gpio /sys/devices/virtual/gpio && chmod -R 770 /sys/devices/virtual/gpio;\
chown -R root:gpio /sys$devpath && chmod -R 770 /sys$devpath\
'"
KERNEL=="ttyAMA[01]", PROGRAM="/bin/sh -c '\
ALIASES=/proc/device-tree/aliases; \
if cmp -s $ALIASES/uart0 $ALIASES/serial0; then \
echo 0;\
elif cmp -s $ALIASES/uart0 $ALIASES/serial1; then \
echo 1; \
else \
exit 1; \
fi\
'", SYMLINK+="serial%c"
KERNEL=="ttyS0", PROGRAM="/bin/sh -c '\
ALIASES=/proc/device-tree/aliases; \
if cmp -s $ALIASES/uart1 $ALIASES/serial0; then \
echo 0; \
elif cmp -s $ALIASES/uart1 $ALIASES/serial1; then \
echo 1; \
else \
exit 1; \
fi \
'", SYMLINK+="serial%c"
root@DietPi:~#
```