The DF771 fault code received in Renault vehicles is related to the fuel pressure regulator, and one of the common mistakes made in this regard is to change the fuel pressure regulator directly without investigating the cause of this error in the vehicle that received the DF771 fault code.
The fuel pressure regulator is a device that controls the pressure of the fuel supplied to the fuel injectors in the engine.
In order for the combustion process in the engine to be regular and controlled, it is necessary to regulate the fuel pressure, and the fuel pressure regulator works for this.
The way the fuel pressure regulator works is as follows:
To check the fuel pressure, it is necessary to drain part of the fuel flow from the fuel pump to the injectors.
The fuel is pumped from the fuel tank to the fuel line by the fuel pump. Immediately after the fuel line is the fuel pressure regulator.
To set the required fuel pressure, the valve on the fuel pressure regulator is opened and part of the fuel is discharged into the fuel tank.
Possible problems with the vehicle with the Renault fault code DF771:
- Decreased engine performance
- The vehicle stops, does not start
- Ejection of black or white smoke from the exhaust
- Increased fuel consumption
- Catalytic converter failure
Brief description of the DF771 fault code: Fuel pressure regulation
It means that the fuel pressure regulation necessary for the operation of the engine cannot be achieved. In this case, the first thing that comes to mind is that the part responsible for regulating fuel pressure may have failed, but the main cause of the problem may be another one.
When the DF771 fault code is received, the problem must be corrected immediately, otherwise the catalytic converter may malfunction.
Causes of DF771 fault code:
- The cable of the fuel pressure regulator may have come loose.
- The connector of the fuel pressure sensor may be rusted, contaminated.
- The fuel pressure regulator may be leaking.
- The fuel pump may be faulty.
- The fuel filter may be clogged.
- The cables to the ECU may be corroded.
- There may be an ECU malfunction.
DF771 Renault fault code solution
- First, it should be checked whether there are problems with the sensor cables or connections. Perhaps there is nothing wrong with the car, the error code may have occurred because the sensors could not read the data correctly.
- If the diesel fuel pressure switch is faulty, the DF771 fault code can be obtained because the fuel pressure cannot be read correctly. This sensor must be checked.
- If there is no wiring error in the vehicle, if the sensors are intact, it is checked whether the fuel pressure regulator performs its function.
- A common problem in this regard is the clogging of the fuel filter or the failure of the fuel pump due to the neglect of periodic maintenance of the vehicle.
- These two aspects also prevent the fuel pressure regulator from doing its job.