Common Rail Fuel System (ACRS™), a variable-speed water pump, and optimized oil pump help maximize fuel economy. The DD15 Detroit engine had the turbo that uses the over ride clutch connected to the rear gears.

If you suspect that this is the case, perhaps after changing the regulator O-ring to find there is no difference to the fault then you must carry out or entrust a garage to do a diagnostic ‘leak-off test’ to prove the injector system is sound. When I checked the fuel pressure at the rail, there was no pressure at all.

Dd15 no fuel rail pressure The spring gets weak and starts to bleed off rail pressure below the pop off pressure and throws this code.