Here is where I got the codes I used for my 2018, guessing the same for yours. Gear selected is the first one.and realized I didn't have the right programming in it to be able to tell what gear the vehicle was in. So still need to figure that out.
ScanGauge II codes for 2020
Anyone have the codes for a 2020 for Gear and Trans Temp? Tried the 2019 codes that someone posted, and VCM works but nothing on TFT and GER. Searched scangauge and cannot find anything for 2020 Ridgeline. Update: The (alternative) trans temps ATF looks like it works in the 2020 instead of...