One for cleaning and one for corrosion control. It's been years so what we used is not in my memory but check your auto parts shelves for this. Worst case is you have to replace the harness or connectors.
So I've been having a p0325 error code for quite a while so I'll bring you up to speed.
Upon research, the 01-05 Rio has bad grounding, so I double checked all the grounds were cleaned and resistances are adequately low. Still got the error code.
I found that one of the 3 wires for the knock sensor were damaged in the wiring harness were damaged, so I fixed that issue. That wire now seems fine from knock sensor wires - pcm.
Now I think another of the knock sensor wires have a resistance that ends up to 1 ohm, so obviously something isn't right. When I unplug the harness connector and check the resistances at either end, everything seems fine. When I plug the connector back in the circuit seems closed with low resistance. Call me crazy, but it seems that over a half hour or so I think the resistance slowly climbs a tenth of an ohm.
The car drives fine for a bit after replugging in the connector, but eventually it codes again and I notice slight drivability issues.
What would cause the resistance to slowly climb like this, if it happens? I've used dielectric grease on the connector to no avail.
If you need clarification on something I said that might be not clear I'll explain!