P0520 on 2013-2016 Chevrolet Malibu 2.5L: Engine Oil Pressure Sensor Circuit Causes and Fixes

What's Unique About the 2013-2016 Chevrolet Malibu

The defining challenge for the P0520 code on the 2.5L LCV engine in the 8th generation Malibu is the physical location of the oil pressure sensor. Unlike many engines where the sensor is easily accessible, GM placed it underneath the intake manifold. This design choice turns what would be a simple, 15-minute repair into a significant job that requires removing the alternator and the entire intake manifold just to gain access, drastically increasing labor time and cost.

Generation note: This guide covers the eighth-generation Chevrolet Malibu (2013-2015) and the 2016 Malibu Limited, which was a continuation of the eighth generation. The fully redesigned ninth-generation 2016 Malibu used a different 1.5L turbo base engine to which this specific guidance does not apply.

Symptoms You May Notice

• Check Engine Light illuminated
• Oil pressure warning light on the dashboard
• Oil pressure gauge on the instrument cluster reading zero, maximum, or an erratic value
• In some cases, the remote start feature may be disabled by the PCM as a safety precaution.
• In rare cases, engine noise if an actual low oil pressure condition exists concurrently

Most Likely Causes

1. Failed Engine Oil Pressure Sensor 🔴 High Probability The sensor itself is a common failure point on many GM vehicles from this era. The internal electronics fail over time due to heat cycles, leading to incorrect voltage signals. Oil can also leak through the sensor body and contaminate the electrical connector.
   How to confirm: After confirming correct oil level and verifying actual mechanical oil pressure is good with a manual gauge, the sensor is the presumed culprit. A scan tool may show a fixed, irrational pressure reading (e.g., 130 PSI) or zero volts/PSI regardless of engine RPM. Due to the sensor's location, direct electrical testing is impractical, making replacement the most common diagnostic step.
   Typical fix: Replace the engine oil pressure sensor. Due to its location, the intake manifold gaskets must also be replaced.
   Est. part cost: $60-$100
2. Damaged Wiring or Connector ⚪ Low Probability The wiring harness is located in a high-heat area in the engine bay. Over time, the plastic connector can become brittle and break, or wires can become frayed or oil-soaked from a leaking sensor.
   How to confirm: Visually inspect the sensor's electrical connector and the surrounding harness for signs of damage, corrosion, or oil contamination once the intake manifold is removed. Check for continuity on the signal, ground, and 5V reference wires.
   Typical fix: Repair the damaged section of the wiring harness or replace the pigtail connector.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare. The PCM should only be considered after a new OEM sensor and verified wiring have failed to resolve the code. A more likely scenario is oil contamination at the ECM connector from a leaking sensor.
• Low Engine Oil Level: While P0520 is an electrical code, extremely low oil levels can sometimes cause erratic readings that trigger a circuit fault before a performance code like P0521 or P0524 is set. Always check the dipstick first.

Diagnosis Steps

1. Check the engine oil level and condition. Ensure the oil is full and not overdue for a change. The 2.5L LCV engine requires SAE 5W-20 dexos-approved oil.
2. Connect an OBD-II scanner to confirm P0520 is the active code and check for other related codes like P0521, P0522, or P0523.
3. Use the scanner to view live data for the Engine Oil Pressure sensor. A reading that is stuck high (e.g., 130 PSI) or at zero, regardless of RPM, strongly suggests a sensor or circuit fault.
4. If possible, connect a mechanical oil pressure gauge in place of the sensor to verify the engine's actual oil pressure. If pressure is within spec, the problem is confirmed to be electrical. This step is often skipped due to the sensor's inaccessibility, proceeding directly to sensor replacement.
5. To access the sensor, disconnect the battery.
6. Remove the air intake ducting and throttle body.
7. Remove the alternator to gain access to the intake manifold.
8. Disconnect fuel lines and electrical connectors, then remove the intake manifold to expose the engine oil pressure sensor.
9. While access is available, inspect the sensor's electrical connector and wiring for any signs of damage, corrosion, or oil contamination.
10. Replace the oil pressure sensor and the single-use intake manifold gaskets.
11. Reassemble all components in reverse order. Torque the intake manifold bolts to 10 Nm (89 lb-in) to prevent vacuum leaks, as per TSB #PIP5529B.
12. Reconnect the battery, clear the trouble codes with the scanner, and perform a drive cycle to ensure the code does not return.

Parts You'll Likely Need

• Engine Oil Pressure Sensor (OEM #12673134) — This sensor is the most common failure point for the P0520 code on this vehicle. The original part number (12621234) has been superseded by this updated part. Using a genuine ACDelco part is highly recommended to avoid premature failure and repeating the labor-intensive repair.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $40-$60
  Aftermarket price range: $25-$50
• Intake Manifold Gasket Set (OEM #12657427) — The intake manifold must be removed to access the sensor. These gaskets are single-use and must be replaced to prevent vacuum leaks after the repair.
  Trusted brands: ACDelco, Fel-Pro
  OEM price range: $20-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P0521 — Indicates the sensor's reading is out of its expected performance range. It shares the same root cause (a bad sensor).
• P0522 — Indicates the sensor circuit voltage is too low. This is often set along with P0520 by the same failing sensor.
• P0523 — Indicates the sensor circuit voltage is too high. A sensor that is failing erratically can trigger this code as well.

Technical Service Bulletins (TSBs) & Recalls

• TSB #PIP5529B: While not for P0520 directly, this TSB is highly relevant to the repair. It addresses a known issue on the 2.5L LCV engine where intake manifold bolts loosen over time, causing vacuum leaks and various trouble codes. It instructs technicians to re-torque the bolts to 10 Nm (89 lb-in), a critical step during reassembly for the P0520 job.

Platform-Specific Known Issues

• Owner Experience: 2014 Malibu P0520: A user on Chevytalk.org with a 2014 Malibu 2.5L reported a P0520 code and an oil pressure gauge pegged at maximum. The confirmed fix was replacing the oil pressure sensor, which required removing the intake manifold. The user noted the difficulty of the job but confirmed it solved the problem.
• Repair Story: High Mileage Malibu: A Reddit user with a 2014 Malibu 2.5L with over 200,000 miles mentioned having to address various sensor and solenoid issues over the vehicle's life to keep it running, which is typical for this platform. While not mentioning P0520 specifically, it fits the pattern of sensor-related repairs being a common maintenance item.

Mechanic-Grade Diagnostic Values

• Sensor 5V Reference Voltage — expected: 4.8V to 5.2V DC with key on, engine off (measured between the 5V reference pin and ground at the sensor connector).. Failure: Voltage below 4.8V or above 5.2V points to a wiring issue, a short on the reference circuit, or a faulty ECM.
• Sensor Signal Voltage (Live Data) — expected: Approximately 1.3V - 2.0V at warm idle, rising towards 4.0V with increased engine RPM.. Failure: A static reading of 0V, 5V, or a value that does not change with RPM indicates a failed sensor or circuit fault.
• Sensor Low Reference (Ground) Circuit — expected: Less than 10 Ohms of resistance to a known good chassis ground. Less than 100mV when back-probing at the connector with the key on.. Failure: Resistance over 10 Ohms or voltage over 100mV indicates a poor ground connection, which can cause erratic readings.

Wiring & Ground Locations

• Engine Oil Pressure Sensor Connector — Under the intake manifold, next to the starter motor. It is a 3-wire, GT150-style connector.. This is the primary connection point. It contains the 5V reference, signal, and ground wires for the sensor. Its location makes it difficult to access for testing.
• G122 — At the rear of the engine on the cylinder head.. This is a primary engine ground. A poor connection here can cause floating or incorrect readings for multiple engine sensors, including the oil pressure sensor.
• G101 — Left front of the engine compartment.. This is a key engine compartment ground. Verifying it is clean and tight is a fundamental step in diagnosing any electrical fault on this vehicle.
• ECM Connectors (X1, X2, X3) — Engine Control Module, located in the engine bay.. A leaking oil pressure sensor can wick oil all the way up the wiring harness and contaminate the pins within the ECM connectors, causing P0520 and other seemingly unrelated codes.

Real Owner Repair Stories

• YouTube channel 'The mech a nic' (2015 Chevrolet Malibu) — Check engine light on with 'Low Oil Pressure, Shut Off Engine' message on the dash. Scan tool showed codes P0521 and P0522. Live data showed 0 PSI and 0 volts from the oil pressure sensor.
  ❌ Tried (didn't work) Cleaning the electrical connector and plugging it back in did not fix the issue.
  ✅ What actually fixed it Replacing the engine oil pressure sensor. After replacement, the scan tool showed oil pressure fluctuating between 38-45 PSI and a signal voltage of 2.0V at idle, which resolved the codes.

OEM Part Supersession History

• 12621234 → 12673134 — Updated part design for improved reliability and durability.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Excessive Oil Consumption 🔴 High — Common issue, particularly as mileage increases. Can be caused by piston ring issues. Must be addressed to prevent catalytic converter failure.
• Stretched Timing Chain 🔴 High — A known issue for the Ecotec engine family, often occurring between 80,000 and 150,000 miles. Presents as a rattling noise on startup and codes like P0016.
• Loose Intake Manifold Bolts 🟠 Medium → Shop Engine Intake Manifold — Common enough to warrant a TSB. Causes vacuum leaks leading to codes like P0171, P0106, and P0506. (Ref: TSB #PIP5529B)
• Failing Camshaft Position Actuator Solenoids (VVT) 🟠 Medium — A frequent failure item, causing codes like P0010, P0011, P0013, and P0014. Relatively easy and inexpensive to replace.
• Brake Vacuum Assist Failure (2014 models) 🔴 High — Specific to 2014 models with the 2.5L engine and auto stop/start. Can cause a loss of brake assist. (Ref: Recall #14V240000)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, using a used part is almost never a smart choice for the sensor itself. The part is inexpensive and the labor to access it is very high (2.5-3.5 hours). The risk of a used sensor failing prematurely outweighs any cost savings. A used wiring harness pigtail from a junkyard is a reasonable choice if the original connector is physically broken during the repair.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For a pigtail connector: Ensure the plastic is not brittle or cracked.
• Check that the locking tab is intact and functional.
• Inspect the pins for any signs of corrosion (green or white powder).
• Ensure the attached wires are flexible and the insulation is not cracked or oil-soaked.

OEM-only on this vehicle (don't cheap out):

• Engine Oil Pressure Sensor. Due to the high labor cost of replacement, using a genuine ACDelco/GM part is strongly recommended by professional technicians and experienced owners. Aftermarket sensors for this application have a documented high failure rate, creating a significant risk of having to repeat the entire job.

Brands owners have reported issues with on this vehicle:

• Unbranded or 'white-box' sensors sold on online marketplaces. While inexpensive, their failure rate is unacceptably high for a part that requires removing the intake manifold to replace.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0521 — A related oil pressure sensor performance code that often appears alongside or instead of P0520 when the sensor provides an irrational reading.
• P0522 — Indicates low voltage in the oil pressure sensor circuit, often caused by the same sensor failure or wiring damage described for P0520.
• P0523 — Indicates high voltage in the oil pressure sensor circuit; frequently triggered when the sensor fails internally and sends a 'pegged' maximum pressure signal.
• P0171 — A lean condition code that can occur if the intake manifold bolts are not properly torqued to 10 Nm (per TSB #PIP5529B) after replacing the oil pressure sensor.
• P0106 — A manifold absolute pressure code related to vacuum leaks, which can be a secondary issue if the intake manifold is disturbed during the P0520 repair.
• P0010 — Relates to the VVT solenoids, which are another frequent failure item on the 2.5L LCV engine alongside the oil pressure sensor.
• P0016 — Indicates a timing chain alignment issue, a known high-severity concern for the Ecotec engine family used in this Malibu.

Frequently Asked Questions