Ok this is the solution I found to work best for me.
I was making a navigation app using OSM and OSR. I kept coming up with the 4003 and 400 error. So I thought thought I'd give Waze a try. Using the following blocks I was able to check whether Waze was installed in their device and if not give them the option to install it direct from the Play Store.
If it was installed on their device, it takes them straight to Waze's brilliant navigation system inc. turn by turn voice.
Hope this helps someone.