Fault code information
1 trip MIL + 1 trip Stop Engine lamp
3 drive cycle recovery
Readiness group – None
Freeze frame type – Fuel
Description of component(s)
Common rail pump units 1–2 (L092–L093)
Common rail pump units 1 and 2 supply fuel to the common rail.
Operation
The internal plunger is actuated via a roller lifter on the camshaft. Each pump has three pump events every two crankshaft revolutions.
Fuel from the fuel gallery can enter the pump plunger area via an internal valve.
A pump event starts when the plunger travels up, the PCI ECU activates the solenoid briefly, and the internal valve closes the opening to the fuel gallery. The internal valve is kept closed hydraulically, and the fuel is pumped to the rail via a check valve in the outlet bore of the pump unit.
The pump event stops when the roller lifter passes the top of the camshaft lobe, causing the plunger to travel downward again. Due to this, the pressure above the plunger decreases and the internal valve opens the opening to the fuel gallery. The check valve in the outlet bore closes and prevents fuel from flowing back from the rail to the plunger area.
Control
The amount of fuel pumped to the rail depends on the duration of the pump event. The earlier the solenoid is activated by the PCI ECU in the up stroke of the pump plunger, the more (mg/stroke) fuel is pumped to the rail
Effect on the system
* Rail pressure control
The rail pressure is closed-loop controlled. A comparison is made between the actual rail pressure and rail pressure demands determined by the ECU. The rail pressure is adjusted by pumping more or less fuel to the rail with the common rail pump units.
Location of component(s)
Common rail pump unit 1 (L092)
Common rail pump unit 2 (L093)
Diagnostic condition
This diagnostic runs when the rail pressure control state is: Pump unit only
Set condition of fault code
The PCI ECU (D420) detects that the actual rail pressure is too low for the duration of the pump events (pump delivery percentage) of the common rail pump units for more than 4 seconds.
Reset condition of fault code
This DTC changes to inactive when the fault is no longer detected.
To validate the repair, drive the vehicle until the coolant temperature is at least 70°C [158°F]. Once the minimum target temperature has been reached, proceed at a minimum speed of 80 km/h [50 mph] in the highest gear possible with the engine speed between 1100 and 1500 rpm and set the cruise control. This test is best performed with a loaded vehicle/trailer, but if load is unavailable, turn as many engine power consumers on to produce engine load. Perform this test for roughly 5 to 8 km [3 to 5 miles] or in 3 separate 1.5 km [1 mile] increments if a steady 5 to 8 km [3 to 5 miles] is unachievable. Use a flat road, if possible.
Electrical diagram(s)
Checking data, common rail pump unit 1-2 (L092-L093)
Technical data
Component check, common rail pump unit 1 (L092)
Preparation
* Key off the ignition
* Disconnect connector L092
* Measure on the component connector L092
Component check, common rail pump unit 2 (L093)
Preparation
* Key off the ignition
* Disconnect connector L093
* Measure on the component connector L093
Possible causes
* Air present in the fuel system.
If the fuel system or parts of it have been emptied during maintenance or repair, this DTC may become active temporarily after the engine is started. If the DTC stays inactive when the engine is running, no further investigation is necessary.
* Malfunction in the low-pressure fuel system
* An external or internal leakage on the high-pressure fuel system components.
* Common rail pump unit failure
Additional information
The common rail pump units (L092 and L093) supply fuel to the common rail. The amount of fuel pumped to the rail (rail pressure) depends on the duration of the pump events of the pump units (pump delivery percentage).
The common rail pump unit control is closed-loop controlled. A comparison is made between the expected and the actual common rail pump unit activation duration.
P228D can also be active when this DTC is active.
When this DTC is active:
* The engine torque is reduced
* The engine runs in protection mode
* The maximum rail pressure is limited to 1300 bar
