P1603 Code failures by brands


Description of DTC code P1603

The fuel system of the vehicle has the function of storing and later supplying this compound. The fuel must be combined with air in the engine's intake system, and in the same place, it is atomized and vaporized so that it can be reduced in the cylinder, and then it is ignited to produce energy or power. Although the fuel systems may be different from one engine to another, they are all the same because their purpose is to supply the fuel to the combustion chamber and to control the amount of fuel sent to the amount of air.

The fuel pressure is regulated depending on the type of system. When it is with the return, a regulator is used that changes the fuel pressure depending on the amount of vacuum in the intake system. In this way, the quantity of fuel pressure and flow as it achieves the injectors remains consistently the same. But in a non-return type system, the PCM (Powertrain Control Module) is used to regulate the fuel supply. A Fuel Pressure Sensor is installed on the rail that supplies the fuel to the injectors to allow the controller to adjust the pressure. When the pressure and flow of fuel drop due to increased engine speed or load, the PCM balances this process by raising the duration of the injector or the operating speed of the fuel pump.

Toyota's establishment of failure code P1603 OBDII indicates that it occurs when the fuel pressure in the rail falls below the threshold, causing the engine to stop.

Symptoms of fault code P1603

  • Check Engine lamp on.
  • Difficult to start the engine.
  • During acceleration, the engine runs slowly.
  • Intermittent loss of motor power.
  • Unstable idling.

Causes of OBD2 P1603

The reasons for setting the DTC code P1603 OBD2 are the following:

  • The amount of fuel available may not be as much as needed.
  • The intake system may be leaking air.
  • The Mass Airflow (MAF) sensor may be defective.
  • Possibly the engine coolant temperature sensor is
  • The fuel pump may have deficiencies.
  • The throttle body assembly may be faulty.

Possible solutions of the DTC code P1603

To solve the diagnostic code P1603 OBDII, you should consider the following:

  • See the Technical Service Bulletins.
  • Check if the vehicle has enough fuel before proceeding with a more advanced diagnosis.
  • Check with an automotive scanner if additional DTCs are configured to P1603 that indicate a failure of a specific fuel system component. Diagnose them in the order shown on the scanner.
  • Check the intake system connections and check the system for air leaks. Repair as necessary.

Codes related to P1603

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