P0520 Code (Symptoms, Causes, and How to Fix)

Engine sensors prevent catastrophic damage, but trigger false alarms if they malfunction. Code P0520 indicates the oil pressure sensor circuit has failed.

This article covers common causes of a P0520 code, symptoms you may encounter, and how to correctly troubleshoot and fix the problem at hand.

P0520 code

What Does Code P0520 Mean?

OBD-II Trouble Code P0520 Description
Engine Oil Pressure Sensor/Switch Circuit Malfunction

Virtually all modern vehicles prove capable of alerting motorists to sudden drops in engine oil pressure. While some vehicles feature a dedicated oil pressure gauge, others utilize a more basic warning light. Nonetheless, data parlayed to these warning devices is obtained through the use of an oil pressure sensor or switch.

Feedback from a sensor of this type is directed to a vehicle’s onboard computer, where it is interpreted, and plotted against the pre-programmed minimum and maximum operating values. Any reading outside of the thresholds triggers a “low oil pressure” warning, which is displayed in a noticeable location upon a vehicle’s instrument cluster.

Like any electrical component, most engine oil pressure sensors and switches are prone to eventual failure at the hands of standard wear and tear. Add in the increased stress imposed by prolonged exposure to heat/vibration, and you have the perfect recipe for electrical component fatigue.

Whenever a vehicle’s ECM/PCM registers feedback from an oil pressure sensor that falls outside of its operating norm, or that proves irrational, diagnostic fault code P0520 is logged, thereby illuminating the vehicle’s check engine light in the process. Simply put, DTC P0520 signifies the existence of an issue within a vehicle’s engine oil pressure sensor circuit.

Related: P0521 Code, P0522 Code, P0523 Code, P06DD Code

Symptoms of Code P0520

oil pressure gauge

Diagnostic fault code P0520 can often be accompanied by a number of secondary symptoms, though on occasion, this fault can occur without any additional symptoms presenting themselves at all. Recognizing the potential symptoms of DTC P0520 can prove invaluable when attempting to diagnose the issue at hand.

The following are several of the most common symptoms associated with DTC P0520.

  • Illuminated check engine light
  • Illuminated oil pressure warning light
  • Lack of oil pressure gauge function
  • Excessive engine noise
  • Reduced engine power
  • Rough or erratic idle

Causes of Code P0520

oil pressure sending unit
Checking oil pressure sending unit connection

Diagnostic fault code P0520 can be caused by a host of underlying issues, some of which prove more common than others. Understanding the potential causes of this fault can quite simply streamline your vehicle’s ultimate return to service.

The following are several of the most common causes of DTC P0520.

Is Code P0520 Serious?

Diagnostic fault code P0520 is generally considered to be quite serious in nature, due to the fact that a condition of this type threatens to compromise a vital engine warning circuit.

This presents a potential situation in which a motorist might find themselves unaware of a critical loss of lubricating engine oil pressure, thereby risking significant internal engine damage.

Additionally, there is also the risk that continuing to operate a vehicle for a prolonged period in this state could void the affected vehicle’s powertrain warranty. At the very least, a vehicle’s manufacturer is highly unlikely to warranty any internal engine failures that occur due to the loss of oil pressure, if a vehicle is knowingly operated for extended periods of time with an active P0520 fault.

In any event, the root cause of a vehicle’s P0520 diagnostic fault code should be diagnosed and remedied as soon as possible. Doing so will restore a vehicle’s ability to monitor engine lube oil pressure in an efficient manner, via its onboard management software.

If you don’t feel 100% confident handling these repairs yourself, schedule an appointment as soon as possible with a reputable service center.

How to Fix Code P0520

check engine oil

The following steps can be followed to assist in diagnosing and repairing the root cause of a vehicle’s P0520 fault code. As always, factory-specific service literature for your particular model of vehicle should be consulted before attempting any such repairs.

#1 – Check For Additional DTCs

Before beginning the diagnostic process, check for the presence of additional DTCs using an OBD2 scanner. Any such faults should be thoroughly diagnosed before proceeding.

#2 – Inspect Engine Oil Level

Begin the diagnostic process by checking your vehicle’s oil level. Top off the affected vehicle’s oil level if below capacity, or alternatively, change your vehicle’s oil if it has surpassed its regular service interval.

Related: Should You Check Oil Level When Hot or Cold?

#3 – Check Pressure With Mechanical Gauge

After ensuring that your vehicle’s oil is in optimal condition and filled to capacity, a running check of the engine’s oil pressure should be conducted. This can be done by connecting a mechanical pressure gauge to an applicable test port, or by removing the engine’s oil pressure sensor, and plumbing a mechanical gauge into the remaining orifice.

All pressure readings should be compared to those specified by your vehicle’s manufacturer. Sub-par pressure readings would be indicative of internal engine issues, or lube oil pump failure.

#4 – Test Sensor Inputs/Output

If all readings taken during the previous step proved satisfactory, all oil pressure sensor inputs, as well as the sensor output, should be assessed. This can be done with the use of a quality digital multimeter.

Again, these readings should be compared to specifications provided by a vehicle´s manufacturer. Out-of-specification readings would indicate an ECM/PCM or power distribution circuit issue, while a questionable output would suggest that the oil pressure sensor itself has failed.

If both input and output values prove satisfactory, then the circuit’s feedback path would likely require further attention.

Josh Boyd

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