Mitsubishi 6M70 - Common Rail Pressure Defect Troubleshooting

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P0251: Common Rail Pressure Defect (warning lamp flashes: 36)
P0253: Common Rail Pressure Defect (warning lamp flashes: 22)
Generation condition
Diagnosis code is generated under either of the following conditions.
(1) MPROP (rail pressure control valve) power supply remains low for 1 second.
(2) The difference between target common rail pressure and actual common rail
pressure remains 30% or more for 10 seconds.
Recoverability
System recovers (power is re-supplied to electronic control unit) if signal becomes
normal when starter switch is turned OFF (2 minutes or more) → ON.
Control effected by electronic control unit
• In the case of above problem (1)
• No specific control is effected.
• In the case of above problem (2)
• Injection quantity is limited. (Output is reduced.)
• Exhaust gas recirculation control is stopped.
• Auto cruise control is stopped.
Inspection
Service data 0C: Difference Common Rail Pressure
Actuator test B9: Fuel Leak Check
Other
• Air-bleeding of fuel system (See “ON-VEHICLE INSPECTION AND ADJUST-
MENT”.)
• Inspection of fuel piping (See “COMMON RAIL”.)
• Fuel filter (See “FUEL FILTER”.)
• Gauze filter (See “ON-VEHICLE INSPECTION AND ADJUSTMENT”.)
• Supply pump (Have work performed by Bosch.)
• Pressure limiting valve (Have work performed by Bosch.)
• Injectors (Have work performed by Bosch.)
Generation condition
Diagnosis code is generated under either of the following conditions.
(1) Common rail pressure sensor voltage remains less than 0.74 V for 30 sec-
onds.
(2) The difference between target common rail pressure and actual common rail
pressure is 30% or more, and MPROP (rail pressure control valve) discharge
rate remains above the specified value for 60 seconds.
Recoverability
• In the case of above problem (1)
• System recovers when common rail pressure sensor voltage remains 0.74
V or more for 5 seconds.
• In the case of above problem (2)
• System recovers when the difference between target rail pressure and ac-
tual rail pressure is 30% or less, or MPROP (rail pressure control valve)
discharge rate remains less than the specified value for 5 seconds.
Control effected by electronic control unit Engine is stopped.
Inspection
Service data C0: Difference Common Rail Pressure
Actuator test B9: Fuel Leak Check
Other
• Air-bleeding of fuel system (See “ON-VEHICLE INSPECTION AND ADJUST-
MENT”.)
• Inspection of fuel piping (See “COMMON RAIL”.)
• Fuel filter (See “FUEL FILTER”.)
• Gauze filter (See “ON-VEHICLE INSPECTION AND ADJUSTMENT”.)
• Supply pump (Have work performed by Bosch.)
• Pressure limiting valve (Have work performed by Bosch.)
• Injectors (Have work performed by Bosch.)
TROUBLESHOOTING <DIAGNOSIS USING Multi-Use Tester>