The common rail fuel system is comprised of two fuel pressure sections: a suction side between the fuel tank and the fuel supply pump and a high-pressure side between the fuel supply pump and the fuel injectors. Fuel is drawn from the fuel tank via a feed pump, then pumped into the fuel rail by two plungers, all of which are internal to the fuel supply pump. This high pressure is regulated by the engine control module (ECM) using the fuel rail pressure (FRP) regulator dependant upon values from the FRP sensor attached to the fuel rail. If the ECM detects that the fuel pressure is lower than the desired value, this DTC will set. This most likely indicates some loss of fuel pressure or intermittently loss of fuel pressure by fuel leak from the high pressure side.

DTC P0093 is a Type A DTC.

DTC P0093 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools Required

Verify the integrity of the fuel system and fuel rail pressure sensor by inspecting for the following conditions:

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, inspect the high pressure side fuel line between the fuel supply pump and the fuel injectors for fuel leakage.

⇒	If a fuel leak for fuel line is detected, repair or replace the fuel line.

2. Ignition OFF, test for 3.24 MPa (200 RPM) of engine compression pressure.

⇒	If less than 3.24 MPa (200 RPM), repair the engine compression issue.

3. Start the engine. If any DTCs set, test and repair those DTCs.
4. Ignition OFF, wait 2 minutes after observing the Actual Fuel Pressure parameter with a scan tool. The actual pressure should be 0 MPa with the engine not running at operating temperature.

⇒	If the pressure difference between the actual and desired pressure are more than 2 MPa, replace the fuel rail pressure sensor.

5. Start the engine. Inspect the fuel line between the fuel tank and the fuel injectors for fuel leakage.

⇒	If a fuel leak for the fuel line is detected, repair or replace the fuel line.

6. Connect the suction side fuel pressure adapter EN-47667 with fuel vacuum/pressure gage assembly J 44638 in series with the filter housing and the disconnected fuel hose. Bleed the fuel system by priming the priming pump until it becomes firm, then crank over the engine for a maximum of 5 seconds. Repeat as necessary until the engine starts.
7. Let the engine run at idle for at least 1 minute. Monitor the fuel vacuum/pressure gage while holding the engine speed higher than 2,500 RPM for a minimum of 1 minute.
8. Observe the fuel vacuum/pressure with a pressure gage. The vacuum/pressure gage ever indicate a larger vacuum than 5 in Hg.

⇒	If vacuum/pressure gage ever indicate a larger vacuum than the specified amount during the test, repair or replace the fuel line/fuel filter/fuel tank.

9. Test the injector for injector balance test with a scan tool.

⇒	If engine noise does not change, replace the fuel injector.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.