🔢
P0520 is a high-severity diagnostic code. Reading the freeze-frame data and any paired codes is the fastest way to narrow it down. See top-rated scanners on Amazon ↗
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🎯 Top Causes & Probability
50%
#1 - Most Likely
Failed Oil Pressure Sensor / Switch
The sensor element drifts out of spec or fails outright. The most common pattern on GM trucks - the sensor sits under the intake manifold and bakes.
🔨 Part
$15-$70
👨🔧 Labor
$60-$280
⚡ DIY Difficulty
Medium
30%
#2 - Check First
Wiring or Connector Issue
Oil-soaked connector or chafed harness near the engine block. The sensor wiring runs through a hot, dirty area and breaks down over time.
🔨 Part
$10-$40
👨🔧 Labor
$50-$160
⚡ DIY Difficulty
Medium
18%
#3 - Less Common
Actual Low Oil Pressure
Worn bearings, a failing oil pump, or low oil level. The sensor is correctly reporting that pressure is too low. STOP driving and verify with a manual gauge.
🔨 Part
$30-$900
👨🔧 Labor
$80-$1800
⚡ DIY Difficulty
Hard
🚗 Most Affected Vehicles
🚫 Is It Safe to Drive?
Be careful. The code itself is usually a sensor or wiring issue, but if the sensor is reading correctly and oil pressure is truly low, engine damage is imminent. Check oil pressure with a mechanical gauge before driving.
🔧 Step-by-Step Diagnosis
- Check oil level first - This takes 30 seconds and can save the engine. Low oil = stop driving.
- Verify with a manual oil pressure gauge - Thread a mechanical gauge into the oil pressure port. Hot idle should read 10-25 PSI; 2000 RPM should read 40-60 PSI on most engines.
- Check sensor wiring - On GM 5.3L, the sensor is under the intake. Look for chafed wires and an oil-soaked connector.
- Compare scan tool oil pressure to gauge - If the dash and scan tool read 0 PSI but the gauge reads 40 PSI, the sensor is bad. If both read 0, you have a real oil pressure problem.
❓ Frequently Asked Questions
Is P0520 dangerous to drive with?
It depends. If actual oil pressure is fine and only the sensor is bad, driving is safe but the oil pressure warning may be unreliable. If real pressure is low, driving even a short distance can wreck the engine.
How do I tell if the sensor is bad or the oil pressure is bad?
Use a manual mechanical oil pressure gauge threaded into the engine. If it reads normal, the sensor is bad. If it reads low, the engine has a real problem.
Why is the GM 5.3L so prone to P0520?
The sensor sits under the intake manifold next to the lifter valley. Heat and crankcase pressure pump oil into the connector, which then shorts the circuit. Replacing it requires removing the intake.
Can I just unplug the sensor?
No. The PCM will keep throwing the code, and you will lose your oil pressure warning, which is one of the most critical engine warnings on the car.
How much to fix P0520 at a shop?
On most cars: $120-$220. On GM 5.3L trucks (intake removal): $280-$450. If actual oil pressure is low, repairs run $1500-$5000+.