P0093

DTC P0093 Fuel System Large Leak Detected

Circuit Description

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 and 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 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 rail pressure is certain pressure low 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.

Condition for Running the DTC

^ DTCs P0089 P0091 P0092 P0192 P0193 P0335 P0642 P0643 P0652 and P0653 are not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.
^ The engine is running.
^ The fuel supply pump control is stable.

Condition for Setting the DTC

Either of following condition is met:

^ The ECM detects that the actual fuel rail pressure is less than 2,600 psi (18 MPa).
^ The ECM detects that the actual fuel rail pressure is dropped more than a threshold after an injection event.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM inhibits accelerator pedal control.
^ The ECM inhibits EGR control.
^ The ECM inhibits DPF regeneration control.
^ The ECM inhibits cruise control.
^ The ECM inhibits PTO control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ An intermittently sticking FRP regulator may have allowed the fuel pressure to become low enough to set this DTC.
^ Normal Actual Fuel Rail Pressure readings on the scan tool with the engine running in neutral at idle is around 3,900 to 4,800 psi (27 to 33 MPa) after warm up.
^ A skewed FRP sensor value can set this DTC. The FRP Sensor on the scan tool should read 0.9 to 1.0 volt after the engine has stopped running for a minimum of 30 seconds.

Notice: This DTC most Likely indicates a loss of fuel pressure by a fuel leak from the high pressure side. Inspect the high pressure side fuel leakage between the fuel supply pump and fuel injector first.

Important: If the fuel tank is empty or near empty, air might be allowed to go into the fuel system. With air in the fuel system, smooth flow of fuel into the supply pump is interrupted and this DTC may set. Perform bleeding of fuel system after refueling.

Test Description

The numbers below refers to the step number on the Circuit / System Testing.

8. This step checks for a fuel restriction by determining if a high vacuum is being pulled on the fuel system during normal operation.

9. This step checks for an air leak on the suction side of the fuel system by determining if a vacuum can be pulled when a fuel line is plugged.

Circuit System Testing DTC P0093