[zroger73]

One difference between 2017-2023 Ridgelines and 2024+ Ridgelines is that Honda changed the first rear differential fluid change down from 15,000 miles to 7,500 miles. But that doesn't explain why yours popped up at 5,300 miles and 40% engine oil life left. Another change is that Honda implemented a 1-year maximum oil change interval. So is it possible that even though you've had your Ridgeline for only 6 months, that it's actually a year old and that's why the code popped up? Is the dealer supposed to reset the Maintenance Minder at time of delivery? Or if a Ridgeline sits for 6 months on the lot, is the new owner going to get what appears to be an early first oil change?

The way it works is that after 310 days (85% of 365 days) since the last reset, the oil life will be "forced" to 15% resulting in a Maintenance Due Soon message.

The timer starts when the vehicle is manufactured. It is not reset by the dealer at any point.

 

[zroger73]

I suspect the OP did not get a "Maintenance Due Soon/Now" message - they just simply noticed that A16 was the maintenance that will be due had they allowed the oil life to reach 15%.

Newer Hondas will show you what maintenance will be due, but it is not actually due until the oil life reaches 15% and the "Maintenance Due Soon/Now" message appears.

I've seem some owners confused by this leading to premature/unnecessary maintenance being performed.

 

[zroger73]

My '24 was almost identical to the OP, MM indicated 40%, but had the A16 code at 5800 miles. I didn't want to wait to 15% for the first oil change, probably even waited too long at 5800. The dealer was surprised about the early rear differential code, usually said after 8000-11000.

For years, Honda has said to ensure proper break-in, do NOT change the engine oil until prompted by the MM.