Hello,
2008 Hino 165 4 cyl
117,000 miles plus idle 4-6 hours per day 1100rpm
Getting P0087 code only on the highway driving at 55 and more uphill
Air and Fuel filters changed (replaced 5 times in last 2 month) DEF dropped and washed and reinstalled. Less then 0.5 psi drop
Dealer blamed...