Step 1 – Read Active Fault Codes
Connect the diagnostic scanner and record all active and inactive fault codes before clearing anything.
Step 2 – Monitor Rail Pressure
Compare Desired Rail Pressure with Actual Rail Pressure while accelerating under load.
Step 3 – Check Low Pressure Fuel Supply
Confirm adequate lift pump pressure, inspect filters, and check for air entering the fuel system.
Step 4 – Test the Fuel Control Actuator (FCA)
Command the FCA with the diagnostic tool or substitute with a known good unit if available.
Step 5 – Inspect Rail Pressure Sensor
Verify sensor readings are stable and wiring has no corrosion or damaged pins.
Step 6 – Check the Pressure Relief Valve
Inspect for leakage or a valve stuck partially open, causing rail pressure to drop.
Step 7 – Road Test
Confirm the repair by monitoring actual versus desired rail pressure under full load.