Hello,
The instructions below show how to read the DTCs on a Honda CIVIC VIII gen. UFO (5D).

Normally, you need HDS (Honda Diagnostic System) hardware for this, but it turns out that you don't need this device to read the error codes.
There is a connector with two pins in the fuse box above the driver's legs, shown in the photo below:

It is a diagnostic socket for reading DTCs on the speedometer display. To enable this function, short the visible pins with each other. For example, you can use aluminum foil rolled into a ball. You can see it in the picture below:

Then turn the ignition on with the key to position 2.
We wait 10 seconds and the display will show (if any) DTCs:

By pressing the [ and ] on the steering wheel, go through the list of faults until the end of the list shown in the picture below:

If there were no faults, the "DTC NO" screen will appear immediately
If you want to erase the error from the computer, press and hold the [SEL / RESET] button for about 10 seconds.
Regards
The instructions below show how to read the DTCs on a Honda CIVIC VIII gen. UFO (5D).

Normally, you need HDS (Honda Diagnostic System) hardware for this, but it turns out that you don't need this device to read the error codes.
There is a connector with two pins in the fuse box above the driver's legs, shown in the photo below:

It is a diagnostic socket for reading DTCs on the speedometer display. To enable this function, short the visible pins with each other. For example, you can use aluminum foil rolled into a ball. You can see it in the picture below:

Then turn the ignition on with the key to position 2.
We wait 10 seconds and the display will show (if any) DTCs:

By pressing the [ and ] on the steering wheel, go through the list of faults until the end of the list shown in the picture below:

If there were no faults, the "DTC NO" screen will appear immediately
If you want to erase the error from the computer, press and hold the [SEL / RESET] button for about 10 seconds.
Regards