Rail press. control valve(PCV) is installed in common rail and controls common rail pressure fast as regulating returning quantity of fuel which is delivered to common rail when fast rise of rail pressure is required like the moment of turning engine ON or when fast relief of pressure is required like at the point of deceleration.
The lower RPCV current is, the more fuel is supplied to common rail. Thus it leads rail pressure to be high. On the contrary, the higher RPCV current is, the less fuel is supplied to common rail.
P0091 is set when "0"A in control circuit of Rail Pressure control valve(integrated with common rail) is detected for more than 0.11 sec.. This code is due to open of short to ground in control circuit or Rail Pressure control valve internal open.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage monitoring
? RPCV circuit
? RPCV component
Enable Conditions
? IG KEY "ON"
Threshold Value
? Short to GND, Wiring open
Diagnostic Time
? 110ms
Fail Safe
Fuel Cut
NO
EGR Off
Fuel Limit
YES
Check Lamp
Rail pressure control valve resistance
Operating frequancy
3.42 ~ 3.78? (20?)
1000Hz(1KHz)