P0520 Engine Oil Pressure Sensor Circuit

Theory of operation code P0520 - this diagnostic is run to verify the oil pressure sensor has a valid zero pressure point (offset check). The oil pressure offset reading is essentially the voltage output of the sensor at atmospheric pressure.

P0520 Engine Oil Pressure Sensor Circuit

Two assumtions are made for this rationality:
1. The oil pressure will always bleed down to atmospheric pressure within a certain time period after the engine has stopped.

2. The oil pressure sensor will have a stable output voltage after key-on and before the vehicle start to crank.

After a calibrated amount of engine off time; enough time to allow the oil pressure sensor to stabilize (bleed down to atmospheric pressure), the oil pressure sensor offset test will be performed at the next ignition on. A reading of the oil pressure sensor output is taken when the ignition is turned to the ''on'' position before engine cranking. Once power is applied to the sensor a delay time approximately 20ms is required before the sensor is powered up and can output a valid reading.

At atmospheric pressure a ''good'' pressure sensor will output a voltage within an upper and lower voltage limit. The lower threshold is greater than zero volts so a circuit check can be performed on the device. The reason there is a span between the limits is because there is a small amount of air behind the diaphragm that varies in volume besed on atmospheric pressure. If it is determined the sensor voltage is outside of these boundaries for a calibrated amount of time, the sensor is invalid and a failure will set.

When monitored:
  • With the ignition on, after the ignition has been off for a minimum of three minutes.
  • Engine speed at zero rpm.

Set conditions:
The Powertrain Control Module (PCM) detects an oil pressure reading that is below 0.29 volts (less than 0 psi), or greater than 0.78 volts (more than 7.1 psi) indicating a stuck sensor.

Default actions:
MIL light is illuminate

Possible causes:
  • Oil pressure sensor.
  • Powertrain Control Module (PCM).

Diagnose code P0520 Engine Oil Pressure Sensor Circuit

Step 1. Check for an active DTC
Turn the ignition onm with the scan tool, read DTC.

Is the DTC active or pending?

YES, go to step 2.
NO, perform the the PCM intermittent condition. (For Jeep/JK engine 3.6 V6 replace Oil Pressure Sensor).

Step 2. Engine Oil Pressure sensor
Turn the ignition off, replace the Oil pressure sensor. Turn the ignition on, with the scan tool, erase DTC in the PCM. Turn the ignition off for at least three minutes, turn the ignition on. Monitor the scan tool for at least two minutes. With the scan tool, read DTC.

Is the DTC active or pending?

YES, go to step 3.
NO, repair complete.

Step 3. Check related PCM and component connections

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