GDI ECM operates fuel pressure control valve with the signal from fuel rail pressure sensor to control optimized RPM and rail pressure. But ECM shows this DTC and enters limp home mode limiting fuel mass and maximum RPM in order to prevent abnormal control of ECM under the bad condition out of target rail pressure range.
Rail pressure monitoring error DTC shows indirectly the status of low pressure fuel and mechanical operating status of high pressure pump and fuel pressure regulator with the signal of rail pressure sensor and fuel pressure regulator.
ECM shows P0088 when the rail pressure is higher than the target rail pressure.
Item
Detecting Condition
Possible Cause
DTC Strategy
Rationality check
Poor return of supplied fuel
Sticking by high pressure of fuel pressure sensor
Enable Conditions
2 minutes later after engine start
Threshold Value
Difference between actual value and target < -1.5 Mpa
Diagnostic Time
3 sec.
MIL ON Condition
3 driving cycle
Fig 1) Normal waveform of RPS at acceleration.