Component Location
General Description
At Commom rail diesel engine, rail pressure regulator is controlled based on rail pressure sensor signal 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 shuts engine down 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 diagnose 1).supplying state of low pressure fuel and 2).mechanical operating conditions of high pressure pump and 3).rail pressure regulator indirectly based on rail pressure sensor output voltage and rail pressure sensor duty. thus, repair relavant to this DTC requires mechanics the total understand of fuel system.
DTC Description
P1188 is set when 1) rail pressure regulator duty is above 79%(rail pressure regulator returning quantity decreases as ECM determinig rail pressure to be low) and 2) actual rail pressure lower than target pressure by 250 bar lasts for more than 1 sec. ECM determine that rail pressure regulator is stuck at opened position.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | ? Voltage monitoring | ? Fuel pressure regulator sticking ? Fuel pressure regulator circuit ? Fuel leakage from injectors ? Abnormal fuel pumping quantity at high pressure pump ? Low pressure pump circuit ? Clogged fuel filter |
Enable Conditions | ? Engine run(when engine speed is above 700RPM) |
Threshold Value | ? Actual rail pressure is lower than target pressure by 250 bar when rail pressure regulator duty is above 79% |
Diagnostic Time | ? 1.0sec |
Fail Safe | Fuel Cut | YES |
EGR Off | NO |
Fuel Limit | YES |
MIL | YES |