B101D: ECU Hardware (Control Module Internal Hardware Performance)
3 vehicles · 3 makes · $100-$900 repair
Most Reported On
B101D is an OBD-II diagnostic trouble code meaning “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). This code is most commonly reported on 2023-2025 Buick Encore GX, 2013-2019 Cadillac XTS, and 2013-2019 GMC Terrain (SLE, SLT, Denali), with repair costs ranging from $100 to $900.
Common Causes
Typical Repair Cost
Based on 3 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
B101D does not use the standard P/B/C/U prefix. It may be a manufacturer-specific code, so verify that a scanner supports your exact year, model and module before buying.
Vehicles Affected (3)
FAQ
What does B101D mean?
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).
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?
Repair costs for B101D range from $100 to $900, depending on the vehicle and root cause.
Which vehicles are affected by B101D?
Au7o has documented B101D across 3 vehicle models from 3 manufacturers: Buick, Cadillac, GMC.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.