P0520 Code: Engine Oil Pressure Sensor/Switch Circuit
The engine computer gets a signal from the oil pressure sensor or switch that makes no electrical sense.
At a glance
Severity: Moderate
- Meaning
- Engine Oil Pressure Sensor/Switch Circuit
- System
- Speed & Idle Control · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $50–$4,000
- DIY difficulty
- Moderate
On engines where the PCM reads oil pressure itself, a sensor (three wires: 5-volt reference, signal and ground) or a simple on/off switch reports it. P0520 is the general circuit code: the signal is missing, erratic or doesn't change the way the PCM expects, for example no difference between key-on engine-off and a running engine. The code alone says nothing about the real oil pressure, so the first job is confirming pressure with a mechanical gauge. Many trucks and SUVs, including GM V8s, Ford trucks and the Chrysler/Jeep 3.6L Pentastar V6, drive the dash oil gauge from this sensor, so a dead or wildly swinging gauge is the typical complaint.
Can I keep driving? Pull the dipstick before driving any further. If the level is right and the engine runs quietly, short trips to the shop are usually fine; if the red oil light stays on together with ticking or knocking, shut the engine off and have it towed.
How to read P0520
- P Powertrain
- 0 Generic (SAE)
- 5 Speed, idle & inputs
- 20 Specific fault
Symptoms
- Oil pressure gauge stuck at zero, pinned at the top or swinging back and forth
- 'Oil pressure low' or 'Check oil' message although the dipstick shows full
- Oil warning light flickering over bumps or when the harness moves
- Check engine light on with no change in how the engine runs
- Engine oil seeping from the sensor body or oil found inside its connector
- On engines with a two-stage oil pump, the pump may be held in high-pressure mode
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failed oil pressure sensor or switch (internal fault or leaking diaphragm)
- Oil-soaked, corroded or loose connector at the sensor
- Harness chafed on a bracket, melted near the exhaust or chewed by rodents
- Oil pressure genuinely low or absent (low level, worn pump)
- 5-volt reference or ground shared with other sensors open or shorted
- Aftermarket replacement sensor with the wrong pressure range
- PCM input circuit fault
Diagnosis step by step
Check oil level and condition first
With the engine off for a few minutes on level ground, the level should sit between the marks. Oil that smells of fuel, looks milky or is far overdue for a change can lower pressure for real, so sort that out before chasing wires.
Tools: Flashlight
Read the oil pressure data
With a scan tool, look at the oil pressure reading key-on engine-off (should be close to 0 psi) and at warm idle. Note the freeze frame and any other sensor codes; several 5-volt sensor faults at once point to a shared reference or ground rather than the oil sensor.
Tools: OBD-II scanner
Confirm pressure with a mechanical gauge
Remove the sensor and screw in a test gauge with the right adapter. A warm engine typically shows around 10–25 psi at idle and 30–60 psi at 2,500 rpm (a rough rule is 10 psi per 1,000 rpm). If the gauge is normal but the PCM reading is not, the fault is electrical.
Tools: Torque wrench, Flashlight
Inspect the connector for oil wicking
Unplug the sensor and look for oil inside the plug. A leaking sensor can push oil up through the wires by capillary action, sometimes all the way to the PCM connector, so follow the harness and clean or replace any oil-soaked section.
Tools: Flashlight, Screwdriver
Check reference, ground and signal
Back-probe the connector key-on: about 5 volts on the reference wire, less than 0.1 V between the ground pin and battery negative, and roughly 0.5 V on the signal with no pressure. A two-wire switch should show continuity to ground with the engine off and open once pressure builds.
Tools: Multimeter
Replace the sensor and verify
Fit an OE-spec sensor, tighten to the specified torque and use sealant only if the service information calls for it. Clear the code, start the engine and confirm the gauge rises within a few seconds and follows engine speed.
Tools: Torque wrench, OBD-II scanner
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace oil pressure sensor in an easy-to-reach location | Yes | $90–$250 |
| Replace sensor under the intake manifold (Pentastar V6, some V8s) | No | $250–$550 |
| Repair oil-soaked connector or harness section | No | $100–$300 |
| Mechanical oil pressure test at a shop | No | $50–$120 |
| Oil pump or bearing repair if pressure is truly low | No | $800–$4,000 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Jeep
On the 3.6L Pentastar V6 (also used in Dodge, Chrysler and Ram models) the oil pressure sensor sits on the oil filter housing in the engine valley, under the upper intake plenum. Replacing it means removing the plenum, and it is worth checking the plastic filter housing for leaks while it is exposed.
Field data
| Jeep | 13 | ||
|---|---|---|---|
| Dodge | 4 | Durango, Challenger, Grand Caravan |
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Depends
Most vehicles turn on the check engine light for P0520, which fails an OBD-II emissions test; a few only show a dash message. Clearing the code right before the test also clears readiness monitors, so repair it and drive a few days first.
Frequently asked questions
Is my engine about to lose oil pressure?
Not necessarily. P0520 describes an electrical problem in the sensor circuit, not low pressure itself. A full dipstick, a quiet engine and a normal mechanical gauge reading mean the engine is fine and only the sensing side needs work.
Why is there oil inside the sensor connector?
The sensor's internal diaphragm has started leaking. Oil then travels up the wiring and can reach other connectors, so replacing the sensor alone is not enough if the harness is soaked.
Can I just leave the sensor unplugged?
No. The gauge and warning light then can't warn you of real pressure loss, the code stays on and some engines hold their variable oil pump in its fail-safe mode, which costs fuel.
My engine has both an oil light switch and a gauge sensor. Which one set P0520?
Some engines use a separate switch for the warning lamp and a sensor for the gauge. Check the wiring diagram for the circuit the PCM actually monitors before buying parts, since the two are often mounted close together.