Clearing codes with engine running:
I use ODB Fusion to monitor various engine PID points and also as a code reader. When I connect the OBD reader and app, it always warns me that connecting with the engine running could cause problems. As doing this is the whole point of the device, I've always just ignored that and assume the Lawyers required the warning.
When I go to clear codes, I get the same basic warning and it says its better/safer to clear codes with only the ignition on but the engine not running. I just went to clear a P0456 code and when I got the warning, I did shut the truck off and tried to clear the codes without the engine running but it didn't seem to work and it just kept trying to reconnect. I then just canceled out and started the truck back up to clear the codes with the engine running. But when the got back into the OBD Fusion app, the codes were cleared.
So, maybe it cleared the codes when I only had the ignition on and then glitched out on the connection or it cleared the codes the first time with the engine running. IDK. My long winded stupid question here is does clearing codes with engine running really risk damaging something? Do I really need to connect the OBD2 with just the ignition on when doing this?