Is this necessary for the car to re-learn all the settings again? I understand the PCM on the 02 is reset by pulling fuse #13 for clock backup with the car off. Any issues with a PCM reset, like entering the radio code again?

 

The long term fuel trim as well as the emission readiness checks are what the computer learns over a period of time. All this is lost with a reset.

Its good to do after cleaning the throttle body (or any work that influences engine behavior) because if your throttle body was bad enough then there will now be a bit better airflow even though the throttle position sensor remains the same. Also your driving habits will be altered if the car has more throttle response. So now the car needs to learn a new fuel trim in order to maintain the correct air to fuel ratio. Your idle may need to be relearned as well.

You can reset the ECU by disconnecting the battery for 30 minutes too. But if you do this you will need to know the radio code. That is the only thing unless you have a picky alarm system.

And don't do it if you have an inspection in the next few weeks and your state has to have you pass all emission readiness codes. The car constantly has to monitor all its systems and they will reset if the ECU resets.

 

ECM/PCM reset only requires the back-up fuse pulled for 10 seconds. There is no need to disconnect the battery for 30 minutes.

https://www.hondaaccordforum.com/for...-ecm-reset-jpg

 

^That saves time for me. Guess I never really looked into it though since I usually disconnect the battery when I'm working on my car anyways.