Troubleshooting - commaai/openpilot GitHub Wiki


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List of On Screen Messages


CAN Errors

Communication Issue between Processes

This error can mean a number of things. Essentially, it means not all the right processes are broadcasting to the comma two.

Common Issues

frontFrame not broadcasting

Rarely, the driver facing camera connector will become loose. When this happens, frontFrame will stop broadcasting - causing the Communication Issue between Processes error. Check if your driver facing camera still works by going to Settings -> Device -> Driver Camera View.

Some process not running

If you are running anything but release2 on your device, it is likely the fork maintainer missed something - or has an error in their DBC file. A good way to check is to SSH into your device and type tmux a

CAN Error

There are some message that the device is not receiving properly. Usually this is resolved by fixing a loose connection.

See Fixing a Connection Issue

Radar Communication Issue

This means the CAN bus that the radar sits on is not being received properly, which often means there is a loose cable somewhere.

See Fixing a Connection Issue

Harness Box Error

Similar to a radar error, this means that a CAN bus is not being received by the device.

See Fixing a Connection Issue


Fixing a Connection Issue

Disconnect and reconnect every connector from every plug. Ensure each plug is firmly seated in its respective connector. Do this for everything! The comma power v2, the harness box, and the OBD-C cable to the comma device.

If the error persists, try flipping the OBD-C connector 180ยบ - Sometimes the device will only accept all data lines from a certain direction on OBD-C connector.

If this doesn't fix the issue, the next step in troubleshooting is to purchase replacement cables and A/B compare.

EON discharges during use, or charges slowly

Get a better USB cable: thicker gauge and shorter length. The panda outputs at 5 volts, but due to cable resistance, there is voltage drop to the point where the EON cannot charge effectively.

Errors Relating to CAN or Not Detecting Ignition

For a cable to work, it must have all pins present. The only specs that do are USB-C 3.1 Gen 2 or USB-C with Thunderbolt. Cables below are recommended and confirmed to work. We ship with a 1.5ft cable for most harnesses, or a 3 meter cable on Nissan and OBD-II harnesses.

Car Unrecognized (Issues with FW Query)

If none of this resolves the issue, it is most likely a bad harness box. Contact support for further assistance, listing the things you tried.

comma three "Fan Malfunction Likely Hardware Issue"

Update the software to version 0.8.16 or higher. comma threes made in 2022 and beyond may have a new fan control chip that requires 0.8.16+.

Rebooting Device / Stuck on comma logo

Very rarely, the comma device can get corrupted during an update or by being unplugged without proper shut down.

If these don't work, or if the device continues to reboot while in 'fastboot' mode, contact support with your troubleshooting steps.

comma two

This is usually fixed by reflashing the NEOS operating system back onto the device.

A guide on how to do this is here for Windows, Mac, or Linux.

comma three

The first thing to try is to disconnect the device from power for 30 minutes and seeing if the issue persists. Do not skimp on the 30 minutes.

If not, the issue may be fixed by reflashing the AGNOS operating system back onto the device.

A guide on how to do this is here for Windows, Mac, or Linux.

'No panda' on comma two

This is caused by the UNO board failing to communicate with the phone inside the comma device. Note: this is always expected when the comma device is powered outside the car.

If the comma device is plugged into the car harness, please proceed.

1. Reboot the comma device a few times

Sometimes the device needs to be rebooted a few times to flash the internal UNO board. Did this fix the issue?

If you're running on a fork, you may have to SSH into your comma two and run make recover in cd /data/openpilot/panda/board

2. Run SSH commands to reset the UNO board

There is a guide on how to SSH here: If you are still stuck, you can ask for help on

cd /data/openpilot

PYTHONPATH=/data/openpilot python -c 'from selfdrive.thermald.thermald import setup_eon_fan, set_eon_fan; setup_eon_fan(); set_eon_fan(3);'

When these commands are run, this error is expected and can be ignored. 'sh: can't create /sys/module/dwc3_msm/parameters/otg_switch: Permission denied'

PYTHONPATH=/data/openpilot python -c 'from selfdrive.thermald.thermald import setup_eon_fan, set_eon_fan; setup_eon_fan(); set_eon_fan(0);'

3. Email support

If those commands still don't solve the issue after a device reboot, email [email protected] with your order # and your troubleshooting steps.

EON Fan Constantly Running

SSH into your device, and attempt to manually control the fan using this command.

cd /data/openpilot && PYTHONPATH=/data/openpilot python -c 'from selfdrive.thermald.thermald import setup_eon_fan, set_eon_fan; setup_eon_fan(); set_eon_fan(1);'

The value in the set_eon_fan function is the fan speed, anywhere between 0 and 3 (zero being off and 3 being the highest). Start with setting 1 and then set 0. (You will get a message about permission denied but the command still runs)

If your fan turns off when setting it to 0, then it is working properly. If it remains on, then your fan module is stuck in a state. Find other cooling solutions in #hw-unofficial on discord.

Advanced Debugging

First SSH into your device. Once you are ssh'd into the device, you can monitor openpilot outputs with tmux
tmux a to attach to tmux window
` + d to exit tmux window (this is changed from the default ctrl-b + d)