Coming soon to a car near you, as some manufacturers will be using SCR to get small diesels to pass Euro 6 tests. If it's working properly, you shouldn't get significant amounts of ammonia in the tail pipe, so stinky buses are likely to be suffering from a defective sensor somewhere.
https://en.wikipedia.org/wiki/Diesel_exhaust_fluid
Coming soon to a car near you, as some manufacturers will be using SCR to get small diesels to pass Euro 6 tests. If it's working properly, you shouldn't get significant amounts of ammonia in the tail pipe, so stinky buses are likely to be suffering from a defective sensor somewhere.