A friend of mine installed a new engine, all the solenoid valves new, rebuilt turbos, new actuator wastegate control, new actuator turbo pre-control, new actuator charge control, new charge relief valves, new injectors, new ignition coils, new pressure regulator, new vacuum hose(small ones), new TPS, new wiring harness, new ignition wires and his old OMP(oil metering pump).When we went for a test drive the car behaved like this: boost pressure sequence was 10-8-0. After 4 days of searching the manuals and testing the car again and again we decide to change the OMP and the car now works perfectly. I want to ask the following. Is it possible when the ECU goes on safe mode due to faulty OMP, not to show any error codes on the checker?