STUCK COMMON RAIL PRESSURE SENSOR
(DTC CODE P0191 / DIAGNOSIS MONITOR CODE 74)

1. Set the starter key to the "LOCK" position and disconnect the common rail pressure sensor connector.
2. Measure resistance between the 2nd and 3rd terminals of the common rail pressure sensor connector (component side).

   
   

   
   

   Standard value: 0.5-3.0 kΩ

    

3. Measure resistance between the 1st and 2nd terminals of the common rail pressure sensor connector (component side).

   
   

   Standard value: 6.5-18.5 kΩ

    

NO Fault in common rail pressure sensor	YES Proceed to [2] Measuring resistance between terminals

1. Disconnect the engine ECU connector.
2. Measure resistance between the chassis GND and the 1st terminal of the common rail pressure sensor connector (vehicle harness side).

   
   

   
   

   Standard value: ∞ Ω

   

   If it is difficult to troubleshoot the connector itself, go to [3] Measuring continuity between terminals.

3. Measure resistance between the chassis GND and the 2nd terminal of the common rail pressure sensor connector (vehicle harness side).

   
   

   Standard value: ∞ Ω

    

NO Faulty harness	YES Proceed to [3] Measuring resistance between terminals

1. Set the starter key to the "LOCK" position and connect the signal check harness.
2. Measure resistance between the terminal E13 and the chassis GND.

   
   

   
   

   Standard value: ∞ Ω

    

3. Measure resistance between the terminal E49 and the chassis GND.

   
   

   Standard value: ∞ Ω

    

NO Faulty harness	YES Proceed to [4] Measuring resistance between terminals

1. Disconnect the signal check harness connectors from the ECU and measure resistance between the terminals E13 and E56.

    

   
   

   Standard value: 2 Ω or more

    

2. Measure resistance between the terminals E49 and E56.

   
   

   Standard value: 2 Ω or more

    

NO Fault in common rail pressure sensor	YES Proceed to [5] Measuring resistance between terminals

1. Connect the signal check harness connectors to the ECU.
2. Measure resistances between the terminals E13 and E49.

   
   

   

   Standard value: 200-250 kΩ

    

NO Fault in engine ECU (ECU connectors)	YES Proceed to [6] Measuring voltage between terminals

1. Turn the starter key "ON" and measure voltage between the terminals E13 and E56.

   

    

   Standard value: 4.5-5.5 V

 

NO Fault in engine ECU (ECU connectors)	YES Replace the engine ECU.

1. Confirm the DTC P0191 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC P0191 is inactive.

   

2. DTC Clear

   • Clear the DTC with Hino DX
   • Confirm the same DTC is not reoccurred

   

P0191 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete