The p0520 Dodge code usually means the engine oil pressure signal is outside the range the PCM expects, and that can point to anything from a failed sensor to a genuine oil pressure problem. I would treat it as a diagnostics job, not a guessing game, because the difference between a cheap electrical fix and a real lubrication fault is huge. This guide shows what the code means, what to check first, which Dodge faults show up most often, and how I would decide whether the car can be driven or needs to stop now.
Key facts to know before you start replacing parts
- P0520 is an oil pressure sensor or switch circuit fault, not a guarantee that the engine has low oil pressure.
- If the red oil warning lamp is on, or the engine is knocking/ticking loudly, I would stop the engine and test pressure before driving again.
- On many Dodge engines, the issue is a sensor, connector, or wiring problem, but low oil, the wrong oil, or a blocked pickup can trigger the same code.
- A mechanical oil pressure gauge is the fastest way to separate an electrical fault from a real lubrication fault.
- UK repair costs are usually modest for a sensor or wiring fix, but can climb quickly if the oil pump, pickup, or internal wear is involved.
What the code actually means on a Dodge
On Dodge vehicles, this fault is tied to the engine oil pressure monitoring circuit. The PCM is looking at a voltage signal from the oil pressure sensor or switch, and it expects that signal to stay within a normal range for the engine speed, temperature, and operating conditions. When the signal looks implausible, missing, or electrically out of range, the code sets.
That matters because the fault can be electrical, mechanical, or both. A bad sensor can send nonsense to the computer. A damaged wire can interrupt the signal. Low oil pressure can also make the sensor reading legitimate, which is why the code should never be dismissed as “just a sensor” without a proper check.
On many Dodge models, especially those with a dashboard oil pressure display, the reading you see is not a mechanical gauge in the old sense. It is often a computer-processed value, so a normal-looking dash reading does not always prove that pressure is healthy. That is why I always separate the warning light from the actual oil pressure test.
What I check first before guessing at parts
I start with the simple things because they catch more faults than people expect. Oil pressure problems often begin with a basic service mistake, a connector issue, or oil that is simply not suited to the engine.
- Oil level - check it on level ground and make sure it is between the marks.
- Oil condition - thick sludge, fuel dilution, or very dirty oil changes the way pressure behaves.
- Oil specification - the wrong viscosity can cause low or unstable pressure, especially when hot.
- Recent service work - if the code appeared after an oil change, filter swap, or engine repair, I would inspect the filter, connector, and wiring first.
- Warning signs - a red oil lamp, ticking, knocking, or rough running changes the job from “diagnosis” to “protect the engine”.
I also want the code list, not just the headline fault. If P0520 appears with related codes such as P0521, P0522, or P0524, the picture gets clearer. Those extra codes can suggest that the pressure reading is not simply out of range, but drifting low or high in a way that points more toward a real oil pressure issue.
If the engine sounds normal, the oil level is correct, and the code is the only symptom, the odds lean toward the sensor or circuit. That is the point where the rest of the diagnostic path starts to matter.
The causes that show up most often
In practice, I see the same handful of faults over and over. The useful part is that they do not all demand the same repair, so narrowing the cause early saves a lot of money.
| Likely cause | Why it triggers the code | What usually confirms it |
|---|---|---|
| Failing oil pressure sensor | The sensor output drifts, sticks, or drops out electrically | Good oil pressure on a mechanical gauge, but bad scan data or intermittent readings |
| Corroded or loose connector | The signal voltage becomes unstable or open-circuit | Oil contamination, bent pins, water ingress, or a warning light that comes and goes |
| Chafed wiring | The circuit shorts to ground, power, or another wire | Visible rubbing, brittle loom sections, or a code that changes when the harness is moved |
| Low engine oil level | The pump cannot maintain stable pressure | Low dipstick reading, leaks, or the code returning after a long cornering or braking event |
| Wrong oil viscosity or poor-quality oil | The pressure curve changes, especially when hot | Recently serviced engine, thicker or thinner oil than specified, or poor hot-idle pressure |
| Blocked oil filter or pickup issue | Flow restriction reduces pressure under load or at idle | Dirty oil, overdue service, or pressure that drops as the engine warms |
| Actual oil pump or internal wear | The engine cannot build the pressure it should | Mechanical gauge confirms low pressure across the rev range |
Some Dodge engines are easier to work on than others. On certain V8 applications, including some 5.7 HEMI setups, the oil pressure sensor is buried enough that the intake manifold area has to come apart for proper access. That does not change the diagnosis, but it does change the labour bill and is one reason I would confirm the fault before replacing anything.
The big takeaway is simple: a bad sensor is common, but a bad reading is not proof of a bad sensor. The mechanical test decides that.
How I would diagnose it step by step
When I want a clean answer, I work from the signal backwards. That keeps me from throwing parts at a code that may only be hiding a wiring or pressure problem.
- Read the code and freeze-frame data - engine speed, coolant temperature, and load at the moment the code set can be very revealing.
- Check the oil level and condition - if the oil is low, contaminated, or the wrong grade, fix that first.
- Inspect the sensor and connector - look for oil in the plug, damaged pins, a loose lock tab, or a brittle loom.
- Clear only if needed for testing - I do not clear and forget; I clear only to see whether the fault returns immediately or under the same conditions.
- Verify real oil pressure with a mechanical gauge - this is the most important split in the whole diagnosis.
- Compare the result with factory specification - specifications vary by engine, so I use the data for the exact Dodge unit in front of me.
As a rough sanity check, many healthy engines will show something like 10-20 psi at hot idle and 40-60 psi around 2,000 rpm, but those numbers are only a guide. The factory figure always wins, and a healthy engine can sit outside those rough ranges depending on design and oil temperature.
If the mechanical gauge shows good pressure and the wiring checks out, I would suspect the sensor itself or the signal circuit. If the gauge confirms genuinely low pressure, the diagnosis shifts immediately to the pump, pickup tube, filter, relief valve, or internal engine wear. That is where the repair decision becomes much more serious.
UK repair costs and when I would stop driving
For a UK owner, the real question is often cost versus risk. A quick scan may be cheap, but a wrong assumption can turn a small repair into a major one.
| Repair or check | Typical UK cost range | What it usually tells you |
|---|---|---|
| Basic diagnostic scan | £40-£120 | Confirms the code, related faults, and freeze-frame data |
| Mechanical oil pressure test | £60-£150 | Separates a sensor fault from a real oil pressure problem |
| Oil and filter service | £70-£180 | Fixes low or contaminated oil, or a bad service fill |
| Oil pressure sensor replacement | £120-£350 | Common fix when pressure is actually fine |
| Sensor wiring or connector repair | £80-£250 | Useful when the issue is intermittent or connector-related |
| Oil pump, pickup, or internal pressure repair | £500-£1,500+ | Needed when the mechanical gauge confirms a true pressure fault |
Those are broad ranges, but they are realistic enough to help you judge the job. Labour climbs sharply if the sensor is awkward to reach, and it is often the labour, not the part, that makes a Dodge oil pressure repair expensive. If the engine requires intake removal or extra strip-down time, the bill changes quickly.
My line in the sand is straightforward: if the red oil light is on, the engine is ticking or knocking, or a gauge test shows low pressure, I would not keep driving it. If it is only the check engine light and the engine runs normally, I would still avoid long trips until the oil level, connector, and actual pressure have been checked properly.
The fixes that usually hold up
The quickest repair is not always the best one. I would rather fix the actual failure path once than replace a sensor and watch the code return a week later.
- Replace the sensor only after a pressure test if the mechanical reading is healthy.
- Repair the connector or pigtail if the plug is oil-soaked, loose, corroded, or heat-damaged.
- Use the correct oil and filter for the exact engine, not just a close match.
- Inspect the loom near hot or moving parts because vibration and heat break these circuits down over time.
- Confirm hot-idle pressure after the fix so the repair is backed by data, not hope.
There is one pattern I see too often: the code is cleared, the sensor is swapped, and nobody checks the actual oil pressure once the engine is hot. That can work when the problem is purely electrical, but it misses a marginal oil pump, sludge build-up, or a blockage that only shows up after the oil thins out. If the engine has high mileage or poor service history, I would be especially cautious about calling it fixed too early.
The checks that keep the warning from coming back
If I had to reduce the whole job to a short decision tree, it would be this: oil level first, pressure second, sensor last. That order is more reliable than guessing from the dashboard or buying parts based on the code alone.
For a Dodge with this fault, the best outcome is usually a clean, boring one: the oil level is corrected, a damaged connector is repaired, or the sensor is replaced after the pressure test proves the engine itself is fine. If the pressure is genuinely low, the right fix is larger, but it is still better to find it early than to wait for bearing damage. I would treat that as the real message behind the code, because once the lubrication system starts failing, the cost rises fast and the margin for delay disappears.
