P0131 on the 2024 Buick Encore GX
Your 2024 Buick Encore GX has set code P0131, meaning the Bank 1 Sensor 1 oxygen sensor is reading below the ECM's expected voltage. The 2024 Encore GX continues with the 1.2L turbocharged three-cylinder (L3T, 137 hp, FWD) or the 1.3L turbo three-cylinder (L3U, 155 hp, AWD). Both are inline engines with a single bank, and Sensor 1 is the upstream O2 sensor between the turbo and catalytic converter.
Symptoms
- Check engine light on
- Slightly reduced fuel economy
- Minor idle roughness
- Subtle hesitation during acceleration
- No immediate drivability emergency
Likely Causes
1. O2 Sensor Defect
On a 2024 model, a factory-defective sensor is the most probable cause. The small-displacement turbo three-cylinders produce high exhaust temperatures relative to their size, stressing the O2 sensor from the start. Manufacturing variations in the sensor can lead to early failure in this demanding environment.
2. Assembly Wiring Issue
A connector not fully seated, a harness pinched near the turbo, or improper routing in the compact engine bay are assembly-related issues that appear in the vehicle's early life.
3. Exhaust Leak
A factory gasket defect at the turbo outlet or downpipe connection introduces air past the sensor.
4. Software Update
GM may have software updates available through GDS2 that refine O2 sensor monitoring for the Encore GX platform.
What to Do
- Schedule a Buick dealer appointment — warranty covers this repair fully.
- Dealer diagnoses with GDS2 and checks for TSBs.
- Avoid DIY repairs that could affect warranty coverage.
Repair Costs
Fully covered under the 3-year/36,000-mile bumper-to-bumper warranty and 8-year/80,000-mile federal emissions warranty. Out of pocket: $140–$300 for sensor replacement.
Summary
Take your 2024 Encore GX to the dealer for a free warranty repair. It's a minor sensor issue quickly resolved.