Use the search functionality on the Yamaha website to locate the YDS-133 product page.
On the product page, look for a section related to software or tools. This is where you are likely to find the diagnostic software. yamaha yds 133 diagnostic software download hot
If you own a pre-2015 Yamaha outboard and plan on keeping it for years, absolutely. Having the ability to diagnose a $30 sensor failure before it leaves you stranded five miles offshore is priceless. Use the search functionality on the Yamaha website