hi all hope you can help....I have a 06 focus and its started to give me an engine fault. the code is P0191, any ideas on what could be causing this????
low diesel pressure 06 1.8tdci focus
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That code refers to a fuel rail pressure sensor range/performance problem, how does it start and run?
thanks for replying, It does not like cold starts but will start up ok, I have not felt any lose of power when driving if thats what your asking? could it be the battery?? if the pump is not getting the full 12v when starting??
cant see it being the battery but a weak one wont help matters, does it take a lot of cranking to cold start?
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it can do when its dropped below 0 through the night. I was thinking about starting by changing the fuel filter it has been 2 years since i changed it
A good place to start, failing that low rail pressure can be caused by a worn pump, although that tends to be worse when hot, or leaky injectors. Does it have an in tank pump, if so can you hear it run when you switch the ignition on?
Peter
Peter
Manufacturer Tech Info website....
What does this mean?
OBD Code P0191refers to
The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM) corresponding to pressure. Strain gauge type sensors are consider passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor. The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder.
Symptoms
Possible sumptoms of OBD code P0191
- Engine Light ON (or Service Engine Soon Warning Light) - Engine will not start
Causes
Possible causes of OBD code P0191
- High fuel pressure - Low fuel pressure - Damaged FRP sensor - Excessive resistance in the circuit - Low or no fuel - Wiring harness connector of the fuel pressure sensor - Fuel Rail Pressure Sensor - Fuel
What does this mean?
OBD Code P0191refers to
The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM) corresponding to pressure. Strain gauge type sensors are consider passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor. The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder.
Symptoms
Possible sumptoms of OBD code P0191
- Engine Light ON (or Service Engine Soon Warning Light) - Engine will not start
Causes
Possible causes of OBD code P0191
- High fuel pressure - Low fuel pressure - Damaged FRP sensor - Excessive resistance in the circuit - Low or no fuel - Wiring harness connector of the fuel pressure sensor - Fuel Rail Pressure Sensor - Fuel
Nice "Simple" test for the FRP Sensor is with the ignition on and sensor plugged connect a multimeter to the center pin of plug and earth. You should get 0.5v and when engine is cranked (turned on starter motor) and starts it should rise to 1.5v or more.
Alternatively if your code reader can read fuel pressure your looking for 280bar or more when cranked to allow vehicle to start.
Alternatively if your code reader can read fuel pressure your looking for 280bar or more when cranked to allow vehicle to start.
thanks for the reply's and the information. it seems to be running ok now with just the filter being changed, but it has got warmer and it seemed to only play up when it has been cold.
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