Rail press. regulator valve(RPRV) 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 RPRV current is, the more fuel is supplied to common rail. Thus it leads rail pressure to be high. On the contrary, the higher RPRV current is, the less fuel is supplied to common rail.
P0091 is set when "0"A in control circuit of Rail Pressure regulator valve(integrated with common rail) is detected for more than specified duration. This code is due to open or short to ground in control circuit or Rail Pressure regulator valve internal open.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Voltage monitoring
? RPRV circuit
? RPRV component
Enable Conditions
? IG KEY "ON"
Threshold Value
? Short to GND - 0.22 sec.
? Wiring open - 0.28 sec.
Diagnostic Time
? Refer to threshold Value.
Fail Safe
Fuel Cut
YES
? Engine shut down
EGR Off
NO
Fuel Limit
Check Lamp
Rail pressure regulator valve resistance
Operating frequancy
3.42 ~ 3.78? (20?)
1000Hz(1KHz)