OBD codes / P0520
P0520
SeriousEngine Oil Pressure Sensor/Switch Circuit
Cautious yes — but check your oil level first, today. If the level is good and the engine sounds normal (no ticking or knocking), it's most likely the sender circuit and short drives are fine. Until real pressure is verified with a mechanical gauge, treat any red oil light as real: if it comes on and stays on, pull over and shut the engine off.
What this code means
P0520 means the computer sees a general fault in the oil pressure sensor (sender) circuit — the signal is out of the expected range or behaving implausibly, without pinning down 'low' (P0522) or 'high' (P0523) specifically. In most cases the problem is the sender itself, its connector, or the wiring: these sensors live on the hot, oily side of the engine and commonly fail or leak internally with age. The critical caveat is that your oil pressure warning system is now untrustworthy — the gauge or light may read wrong in either direction — so you must verify oil level immediately and confirm actual pressure before assuming it's just electrical. A shop does this by threading a mechanical gauge into the sender's port; good mechanical pressure means you can fix the circuit at leisure, while low mechanical pressure turns this into an urgent engine problem. Never dismiss an oil pressure code on faith.
Symptoms you might notice
- Oil pressure gauge reading erratic, zero, or pegged high
- Oil pressure warning light on or flickering (possibly falsely)
- Check-engine light
- Usually no change in how the engine runs
- Sometimes oil seepage around the sender
What it costs to fix
Typical range: $50–$250 · about ~0.3–1 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Oil pressure sender replacement | $20–$100 | ~0.3–1 hrs |
| Wiring / connector repair | $5–$80 | ~0.3–1 hrs |
| Mechanical oil pressure verification | $0–$0 | ~0.5–1 hrs |
The sender is a cheap part; cost depends on how reachable it is — some are right on top, others hide behind the intake or exhaust. The mechanical pressure check is worth its labor: it's what separates a cheap sensor swap from a serious engine diagnosis.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0520 for my exact vehicle →
Frequently asked
Is P0520 just a bad sensor or real low oil pressure?
Usually the sender or its wiring — but you can't know from the code alone, and the price of guessing wrong is an engine. Check the oil level now, listen for ticking or knocking, and have actual pressure confirmed with a mechanical gauge before writing it off as electrical.
Can I keep driving with P0520?
If the oil level is correct and the engine sounds normal, short careful driving is generally OK while you arrange the fix. But your pressure warning system is currently unreliable — so if the red oil light comes on or you hear new engine noise, stop immediately.
How does a shop confirm whether the sensor is lying?
By removing the sender and threading a mechanical gauge into the same port, then reading pressure directly at idle and at higher rpm. If mechanical pressure is in spec while the electrical reading is nonsense, the sender or circuit is confirmed as the fault.
How is P0520 different from P0522 and P0523?
All three are sender-circuit codes. P0520 is the generic 'circuit fault' version, P0522 means the circuit voltage is specifically low, and P0523 means it's specifically high. None of them, by themselves, prove the engine's actual oil pressure is bad — that always needs mechanical verification.
Seeing P0520 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0520 for my vehicleSymptoms that trigger P0520
Drivers who get this code often notice one of these — each has its own likely-causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0520 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.