P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE





For a complete wiring diagram Refer to Section 8W.


  • When Monitored:

    Engine running.

  • Set Condition:

    The engine oil pressure never reaches the calibrated specification with the engine RPM at 1250. One trip fault.


Possible Causes
  
ENGINE OIL/ENGINE MECHANICAL
  
EXCESSIVE RESISTANCE IN THE (G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT
  
EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
  
EXCESSIVE RESISTANCE IN THE (K900) SENSOR RETURN CIRCUIT
  
ENGINE OIL PRESSURE SENSOR
  
PCM
  

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1.ACTIVE DTC

NOTE: Make sure that the engine oil is at the proper level. Also, check the customers oil change history to ensure that the oil is being changed at the correct intervals and that the proper oil viscosity is being used.





Is the DTC Active at this time?

Yes
  • Go To 2


No

2.ENGINE OIL/ENGINE MECHANICAL

NOTE: The following items must be considered before determining the cause of this DTC. Failure to do so may lead to misdiagnosis.

  • ENGINE MECHANICAL TOLERANCES OUT OF SPECIFICATION
  • ENGINE OIL PRESSURE OUT OF SPECIFICATION
  • LOW ENGINE OIL
  • OIL DIRTY OR DETERIORATED (Lack of scheduled oil changes)
  • ENGINE OIL CONTAMINATED (i.e., coolant and/or fuel)




Were any of the above conditions present?

Yes


No
  • Go To 3

3.ENGINE OIL PRESSURE SENSOR








NOTE: Engine Oil Pressure voltage should change from approximately 4.5 volts to less than 0.5 of a volt.



Is the voltage reading within the listed specification when the jumper wire is installed?

Yes
  • Remove the Engine Oil Pressure sensor and ensure the oil passage/port is free from any blockage. If OK, replace the Engine Oil Pressure Sensor.
  • Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)


No
  • Go To 4

  • NOTE: Remove the jumper wire before continuing.


4.EXCESSIVE RESISTANCE IN THE (G6) ENGINE OIL PRESSURE SIGNAL CIRCUIT




CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.



WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.





Is the voltage below 0.5 of a volt?

Yes
  • Go To 5


No

5.EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT





WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.





Is the voltage below 0.5 of a volt?

Yes
  • Go To 6


No

6.EXCESSIVE RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT



WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.





Is the voltage below 0.5 of a volt?

Yes
  • Go To 7


No

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.




Were there any problems found?

Yes


No