Follow us on Twitter and win Autohex II Scan Tool for Kia and Hyundai (worth 945.00 USD)

As inputted rail pressure sensor signal, ECM of Commom rail diesel engine controls fuel metering unit(MPROP-intergrated with high press. pump) and rail pressure control valve(PCV-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 diagnose 1).supplying state of low pressure fuel and 2).mechanical operating conditions of high pressure pump and 3). RPCV indirectly based on RPS output voltage and RPS duty. thus, repair relavant to this DTC requires mechanics the total understand of fuel system.

When too many correction signals are loaded to PCV, PCV fails to be controlled and its governing voltage is fixed to certain value. If this condition lasts for more than 5 sec. P1173 is set then, rail pressure is controlled by FPRV alone.