Rail pressure 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 rail pressure regulator valve current is, the more fuel is supplied to common rail. Thus it leads rail pressure to be high. On the contrary, the higher rail pressure regulator valve current is, the less fuel is supplied to common rail.
P0091 is set when "0"A in control circuit of PRV (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 PRV internal open.
Item
Detecting Condition
Possible Cause
DTC Strategy
Voltage monitoring
PRV circuit
PRV
Enable Conditions
IG key ON
Case 1
Threshold Value
Short to ground in PRV control circuit.
Diagnostic Time
220ms
Case 2
Open in PRV control circuit. - Engine Shut off.
280ms
Fail Safe
Fuel cut
YES
-
EGR Off
NO
Fuel Limit
Check Lamp
ON
Rail pressure regulator valve resistance
Operating frequancy
3.42 ~ 3.78? (20?)
1000Hz(1KHz)
Fig.1) The sensor signal waveform at acceleration and no load.