P0521 on Buick: How to Diagnose & Fix
Engine Oil Pressure Sensor/Switch Range/Performance
2 Buick models · 2 documented issues · 2 critical · $180-$650 repair
P0521 on Buick by model: symptoms, diagnosis and fix
On Gen1 Envisions the crankcase ventilation (PCV) valve integrated into the cam cover sticks or fails, letting unburned fuel wash past the rings and accumulate in the crankcase. Owners find the oil level rising above the full mark, a strong gasoline smell in the oil, and a rich-running check engine light. GM addressed it with TSB 18-NA-246, which pairs a PCV valve replacement and oil change with an ECM recalibration. Left alone, the diluted oil loses viscosity and accelerates bearing and timing-chain wear.
Common Symptoms
- Engine oil level rises above the full mark between changes
- Strong gasoline odor in the engine oil
- Check engine light on
- Rough idle or reduced fuel economy
- Thin, watery-looking oil on the dipstick
How to Fix
Follow GM TSB 18-NA-246: replace the PCV valve/cam cover assembly, perform an oil and filter change with the correct spec oil, and reprogram the ECM with the updated calibration. Re-check oil level after several hundred miles to confirm the level is no longer climbing. If dilution ran long, inspect the timing chain for stretch before returning the car to service.
Sources for this issue (2)
The second-generation Encore GX uses 1.2L and 1.3L turbocharged three-cylinder engines and has drawn complaints of reduced engine power, stalling, and lurching. GM issued a recall in which the engine control module (ECM) could fail to clear the permanent status of DTC P0521 (engine oil pressure sensor performance), masking a real low-oil-pressure condition; the remedy is an ECM reprogram. Owners also report elevated oil consumption on these small turbo engines.
Common Symptoms
- Reduced engine power
- Engine stalling
- Lurching / jolting
- Oil pressure warning not displaying
- Elevated oil consumption
How to Fix
Have the ECM reprogrammed under the GM recall to ensure low-oil-pressure conditions (P0521) are properly flagged. Diagnose stalling/power-loss with a scan tool. Monitor oil level frequently given the small-displacement turbo's sensitivity to low oil.
Sources for this issue (1)
P0521 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0521 mean on a Buick?
P0521 stands for "Engine Oil Pressure Sensor/Switch Range/Performance." This code indicates the engine oil pressure sensor or switch is sending a reading that is implausible or out of its normal operating range — for example, the value doesn't match what the engine's speed and conditions should produce. Unlike a simple circuit fault, this means the signal is present but doesn't make sense (range/performance). It can be caused by a failing sensor, wiring issues, or by genuinely abnormal oil pressure. Because oil pressure protects the engine, a true low-pressure reading should be confirmed and taken seriously. On Buick it is documented across 2 models: Envision, Encore.
What are the most common causes of P0521?
The most common causes of P0521 are: Faulty or worn oil pressure sensor/switch, Low engine oil level or actual abnormal oil pressure, Wiring or connector corrosion/damage at the sensor, Sludge or debris affecting the sensor reading, Use of incorrect oil viscosity, Failing oil pump, Poor electrical ground. The specific cause varies by vehicle.
How much does it cost to fix P0521 on a Buick?
Published repair estimates on Buick range from $180 to $650 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0521 on a different make?
View P0521 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.