B101D on Buick: How to Diagnose & Fix
ECU Hardware (Control Module Internal Hardware Performance)
1 Buick model · 1 documented issue · 1 critical · $200-$600 repair
B101D on Buick by model: symptoms, diagnosis and fix
On later Encore GX models the Lane Keep Assist with Lane Departure Warning system applies an inappropriate steering torque that pulls the vehicle across the centerline rather than back into the lane. NHTSA complaints describe a sudden, forceful takeover of the steering wheel toward oncoming traffic, requiring the driver to fight the system. CarComplaints lists Lane Assist as the leading reported problem on the 2025 model year. The behavior appears tied to camera misinterpretation of lane markings - faded lines, tar seams, construction striping, shadows and crest transitions - compounded by camera calibration that was never performed or was performed incorrectly after a windshield replacement.
Common Symptoms
- Steering wheel jerks or grips forcefully toward the centerline
- Vehicle steers toward oncoming traffic without driver input
- Repeated false lane departure alerts on clearly marked roads
- System activates over tar seams or old lane markings
- Behavior worsened after a windshield replacement
How to Fix
Have the front camera module recalibrated - this is mandatory after any windshield replacement and is the most common root cause of biased lane centering. Verify the camera's mounting bracket is fully seated and the windshield in front of it is free of distortion or an aftermarket tint strip, and confirm the vehicle is on the latest camera/ADAS module software, since GM addresses lane-centering behavior through calibration files. Check tire pressures and alignment, because a mechanical pull the system compensates for changes its torque output. Until it is corrected, Lane Keep Assist can be disabled through the vehicle settings menu; report the incident to NHTSA, since ADAS defects are only investigated when complaint volume builds.
Sources for this issue (2)
B101D 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 B101D mean on a Buick?
B101D stands for "ECU Hardware (Control Module Internal Hardware Performance)." General Motors body-code definition. When power-up is commanded, the control module runs an internal self-test that requires only battery voltage, ignition voltage and ground; that test runs even when supply voltage is outside the normal operating range. B101D sets when the module detects an internal hardware malfunction during that self-test — the failure is inside the ECU itself, not in an external sensor or actuator. The two-character symptom suffix (e.g. B101D-00, -31, -39, -3B, -F0) narrows which internal element failed. Because this code can be stored by any GM body module, the affected function depends on which module reported it (e.g. a Power Steering Control Module for a lane-keep/steering complaint, a Seat Module for a Safety Alert Seat complaint). On Buick it is documented across 1 model: Encore GX.
What are the most common causes of B101D?
The most common causes of B101D are: Internal failure of the reporting control module (ECU hardware fault) — the module is normally replaced and programmed, Corrupt or incomplete software/calibration in the module after a failed SPS programming event, Severe under- or over-voltage events, jump-start spikes or a failing battery stressing module internals, Water intrusion or corrosion inside the module housing, Poor power/ground supply to the module causing repeated resets. The specific cause varies by vehicle.
How much does it cost to fix B101D on a Buick?
Published repair estimates on Buick range from $200 to $600 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 B101D on a different make?
View B101D 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.