FL -410
FUEL SYSTEM
DTC P1171 MINIMUM RAIL PRESSURE EXCEEDED
COMPONENT LOCATION
E58ECD38
Fuel Pressure
Regulator Valve
FTS
Rail Pressure Regulator Valve
RPS
LFIG475A
GENERAL DESCRIPTION
E3669CDD
As inputted rail pressure sensor signal, ECM of Commom rail diesel engine controls fuel metering unit(FPRV-intergrated
with high press. pump) and rail pressure control valve(RPRV-integrated with common rail) in order to maintain optimum
rail pressure according to current engine rpm and load. However when the problem that leads rail pressure to out of target
value intended by ECM occurs due to mechanical or electronical reason, ECM limits engine performance and sets DTC by
limiting fuel (stops injector operation) in order to prevent engine from being controlled abnormally. "rail pressure monitoring
error" is the DTC which diagnoses 1) supplying state of low pressure fuel and 2) mechanical operating conditions of high
pressure pump and 3). RPRV indirectly based on RPS output voltage and RPS duty. Thus, repair relavant to this DTC
requires mechanics the total understand of fuel system.
DTC DESCRIPTION
E54C6EAC
Rail pressure is controlled by 1)only RPRV or 2)both RPRV and FPRV or 3)only RPRV depending on engine condition.
These three modes are called ’CPC mode’. During transition from one mode to another mode, if rail pressure is below
the minimum rail pressure for each certain engine condition for more than 300ms. P1171 is set then, rail pressure is
controlled by RPRV alone.
DTC DETECTING CONDITION
E8E237BC
Item
Detecting Condition
Possible Cause
DTC Strategy
• Signal monitoring
Enable Conditions
• Engine running
Threshold Value
• If rail pressure is below the minimum rail pressure for
each certain engine condition
Diagnostic Time
• 0.3 sec.
Fuel cut
NO
EGR Off
NO
Fuel Limit
NO
Fail Safe
Check Lamp
NO
• Rail press.
is controlled
by RPRV
• ECM internal
error
• RPRV
component
• FPRV
component
• RPS
componet