Fix P0520: Mechanic’s solutions that WORKED

The P0520: Engine Oil Pressure Sensor/Switch Circuit Malfunction code indicates an issue with the circuit of the engine oil pressure sensor or switch. This sensor plays a vital role in monitoring the engine’s oil pressure, ensuring the engine is properly lubricated. A malfunction in this circuit can lead to incorrect oil pressure readings, which can be detrimental to the engine’s health and performance.

P0520 quick overview

Description	P0520: Engine Oil Pressure Sensor/Switch Circuit Malfunction
Is it serious?	This code can be serious as it relates to the engine’s oil pressure, which is crucial for proper engine lubrication and protection.
Possible causes	– Faulty oil pressure sensor or switch – Wiring or electrical issues related to the oil pressure sensor – Engine oil level too low or too high – Engine mechanical issues affecting oil pressure – Blocked oil passages in the engine
How to diagnose?	Check Oil Level and Quality: Verify the engine oil level and condition. Inspect Oil Pressure Sensor: Look for signs of damage or leaks at the oil pressure sensor. Examine Wiring and Connectors: Check the sensor’s wiring and connectors for damage or loose connections. Test Sensor Functionality: Use diagnostic equipment to test the oil pressure sensor’s operation. Evaluate Engine Condition: Consider additional diagnostics for engine health if oil level and sensor check out fine.

How to fix P0520 – learn from mechanics

I looked into P0520 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chrysler

Vehicle Information: 2013 Chrysler 300 C 3.6L, MIL Lamp on

Issue + Repair History:

• The car displayed a MIL (Malfunction Indicator Lamp) alert.
• P0520 Engine Oil Pressure Sensor Circuit issue was identified.
• Sensor resistance was tested in ohms with specific readings: Ref. – Grd. 13, Ref. – Sig. 7.5, Grd. – Sig. 7.5.
• Voltage tests on the harness side showed: Ref. 5, Grd. 0, Sig. 5.
• Continuity test between the Ref. and Sig. wires with the battery and ECU disconnected revealed an Open Loop.
• Concern raised about 5v on the Signal wire with sensor disconnected and no continuity between Ref. and Sig. wires, questioning the need for an ECU replacement.

Other OBD2 Codes + Test Results:

• P0520 – Engine Oil Pressure Sensor Circuit.
• EOP Sensor Test Results: Ref – 5v, Sig – 5v, Sig. ground – 0v.

Suggestions to Fix Issue:

1. Confirm if 5 volts on the signal wire is normal.
2. Short the signal wire to ground through a test light to see any change.
3. Consider replacing the oil pressure sensor with an OEM part.
4. Check if the oil pressure sensor is aftermarket and its compatibility.
5. Replace the oil cooler assembly, which includes the pressure sensor.
6. Examine the sensor connector for proper connection, especially if it’s not OEM.
7. Inspect and possibly replace the spark plugs exposed by intake removal.

Final Fix: The issue was resolved by replacing the Engine Oil Pressure (EOP) sensor. It was determined that the PCM’s bias of 5v on the signal wire for calibration purposes was normal, but the PCM was not satisfied with the existing EOP sensor. The replacement aligned with most community recommendations for this specific code, which sets at Key On Engine Off (KOEO).

Case #2: Jeep

Vehicle Information: 2014 Jeep Wrangler Unlimited Sahara 3.6L, MIL Lamp on

Issue + Repair History:

• Vehicle showed codes P0520 and P06DE.
• KOEO (Key On Engine Off) oil pressure was 99 psi, and the PCM (Powertrain Control Module) read 4.57 volts from the 5-volt reference.
• Previous issue with the oil pressure sensor, which was replaced.
• Harness integrity was previously tested and passed.
• TSB (Technical Service Bulletin) 18-034-14 REV A was performed.
• Question raised about the high failure rate of these sensors, even when using Mopar parts.

Other OBD2 Codes + Test Results:

• P0520 – Engine Oil Pressure Circuit.
• P06DE – Engine Oil Pressure Control Circuit Stuck On.
• 5-volt reference and PCM ground were present.
• Oil level was full.

Suggestions to Fix Issue:

1. Replace the oil pressure sender, as this issue is common in Dodge/Jeep vehicles.
2. Consider installing an updated sender as per the Chrysler TSB.
3. Check the wiring and pigtail if the issue persists after replacing the sender.
4. Replace just the sensor, not the entire oil filter housing assembly.
5. Use OEM parts for replacement as aftermarket sensors might not be effective.
6. Inspect for any chafing or damage around the harness behind the left cylinder head.

Final Fix:

• Replacing the sensor with the latest version (P/N 05149062AB) fixed the vehicle issue.
• The decision was made to replace only the sensor, not the entire assembly, based on past wiring integrity checks and TSB guidelines.

Case #3: Chevrolet

Vehicle Information: 2004 Chevrolet Venture LS 3.4L, Poor Idle Quality, Cuts out, Stall

Issue + Repair History:

• Initially presented as a non-start condition.
• Replaced the fuel pump as per diagnosis but still had a crank no-start issue.
• Codes P0463 (fuel level circuit) and P0446 (vent control) were persistent, and the fuel level gauge was malfunctioning.
• Found a blown fuse in the power distribution box feeding the ICM (Ignition Control Module).
• Replaced ICM and a cracked coil.
• Engine started after adding oil but displayed erratic behavior like stalling and popping sounds during acceleration.
• Various diagnostics (vacuum gauge, scan, and scope) showed no apparent issues with TPS, IAC, crank sensors, cam, EGR, spark, MAP, or vacuum leaks.
• The vehicle would run for an unpredictable duration and then stall, often followed by difficulty in restarting.

Computer Codes & Descriptions:

• P0128 – Coolant Thermostat.
• P0141 – O2 Heater Bank 1 Sensor 2.
• P0300 – Random Misfire.
• P0446 – EVAP Vent Control Problem.
• P0463 – Fuel Level Circuit High Open.
• P0520 – Oil Pressure Switch.

Suggestions to Fix Issue:

1. Improve clarity and detail in diagnostic reporting for better understanding.
2. Clear all codes and approach the issue afresh.
3. Verify oil level as low oil might be triggering a shutdown to protect the motor.
4. Investigate the cause of fuel level and vent codes, especially after fuel pump replacement.
5. Check fuel volume and consider the possibility of a faulty new fuel pump.
6. Perform an amp load test on the fuel pump circuit.
7. Bypass the fuel pump relay to test its effectiveness under load.
8. Suggest replacing the crank sensor on the right side of the block.

Final Fix:

• The problem was resolved by replacing and programming the security module, which restored the starter enable signal at the PCM (Powertrain Control Module).

Case #4: Pontiac

Vehicle Information: 2008 Pontiac Grand Prix 3.8L, No Start

Issue + Repair History:

• Vehicle towed in with no start condition.
• Fuel pressure checked and found normal (55psi).
• No spark observed.
• Scanned for codes and found P0520 (engine oil pressure sensor).
• Visual inspection revealed visible cracks in the coil.
• RPM signal was absent.
• Planned to check all fuses and relays.
• Suspected that vehicle might need a CKP (Crankshaft Position) sensor and coils replacement.
• After replacing the CKP sensor, RPM signal was restored, but there was still no spark. A newly installed coil was found to be cracked and overheated.
• Decided to replace the ignition control module (ICM) and another coil as well.

Computer Codes & Descriptions:

• P0520: Engine oil pressure sensor signal circuit

Other Test Results:

• Fuel pressure: 50-60 psi, normal at 55 psi

Suggestions to Fix Issue:

1. Inspect the CKP sensor harness for contact with the crank pulley.
2. Replace all three coils and the ignition module due to potential shorting.
3. Check the ECM for RPM signal to create spark; start with the CPK sensor and closely inspect the wire harness.
4. Consider replacing the ignition control module.
5. Inspect wires near the oil pressure switch and CKP for potential damage due to oil leaks.
6. Check for a bad connection in the fuse box at the crank fuse.
7. Scope the crank angle sensor to analyze the pattern.

Final Fix:

• The vehicle was fixed by installing a new CKP sensor for the RPM signal and replacing the ICM & ignition coil for the spark issue.

Case #5: Pontiac

Vehicle Information: 2003 Saturn Ion-2 2.2L, Crank no start

Issue + Repair History:

• Vehicle bought as non-running.
• Experienced bogging down in rain before completely dying days later.
• Found codes P1599, P0326, P0520, B1327, and U1301.
• Initial attempts to crank resulted in a sputter, then just cranking.
• Fuel pressure at 55psi, spark present, RPM signal available.
• Compression around 140 on all cylinders.
• Timing seemed correct upon visual inspection, chain tight.
• Exhaust was dropped pre-cat with no change, and vehicle did not fire with starting fluid.
• Confused and at a loss for a solution.

Computer Codes & Descriptions:

• P1599: Engine stall or near stall detected
• P0326: Knock sensor circuit voltage
• P0520: Engine oil pressure sensor/switch malfunction
• B1327: Device power number 1 circuit
• U1301: Class 2 short to battery

Other Test Results:

• Fuel pressure: 55psi
• Injectors: Have pulse
• Compression: Around 140 on all
• Spark: Present

Suggestions to Fix Issue:

1. Check if the motor has a low oil pressure shut-off feature.
2. Inspect for moisture in connectors or harnesses, especially those affecting oil and knock sensors.
3. Verify timing, especially with the ignition control module.
4. Examine for damaged ground connections, particularly in the main loom to the transmission.
5. Test the spark using an HEI ignition tester and perform a cylinder leakdown test.
6. Consider the possibility of bad gas or water in the fuel.
7. Check for a possible security key issue or aftermarket alarm installation.
8. Explore the possibility of a bad connection in the fuse box at the crank fuse.
9. Inspect spark plugs for fouling or damage.
10. Investigate if the BCM and ignition switches are functioning correctly.

Final Fix:

• The issue was resolved by addressing a jumped timing chain. Although the chain appeared to be in place and tight, it was a few teeth off. Replacing the chain and tensioner resolved the issue.

Common Advice	Brief Description of Diagnostic Step
Check Timing and Timing Components	Verify the accuracy of the engine’s timing, inspect timing chains or belts, and examine tensioners for proper operation.
Inspect for Spark and Spark Quality	Ensure the presence of a spark at the spark plugs and assess its strength and consistency.
Evaluate Fuel System Pressure	Measure the fuel pressure to ensure it is within the manufacturer’s specified range, indicating proper fuel system functionality.
Examine Sensor Connections and Wiring	Check the connections and wiring of critical sensors like the crankshaft position sensor, oil pressure sensor, and knock sensor for faults.
Consider Potential Electrical Issues	Investigate electrical components such as fuses, relays, and ignition switches for any faults that might affect the engine’s starting or running.
Review Engine Compression	Conduct a compression test on each cylinder to ensure that the engine has adequate compression for normal operation.
Look for Signs of Fuel or Water Contamination	Check the fuel quality for any signs of contamination or water, which can adversely affect engine performance.