B3927 on 2018-2024 Buick Enclave: No Start & 'FOB Not Detected' Causes and Fixes

What's Unique About the 2018-2024 Buick ENCLAVE

The second-generation Buick Enclave and its GM C1XX platform mates (like the Chevrolet Traverse and GMC Acadia) use a specific 'GEN3R' Body Control Module (BCM) that is susceptible to memory corruption after a low-voltage event (like a weak battery or jump-start). While on other vehicles a communication code might point to a failed module or wiring, on this platform, B3927 is almost exclusively a software issue. GM has issued specific Technical Service Bulletins (TSBs) warning technicians NOT to replace the BCM, but instead to perform a special reprogramming procedure to resolve the issue.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Vehicle will not crank ('No Crank, No Start').
• Engine starts and then immediately stalls.
• A 'No FOB Detected' or 'Key FOB Not Detected' message appears on the driver information center.
• Key fobs are completely inoperative and cannot lock or unlock the doors.
• Multiple warning lights may be illuminated on the instrument cluster.
• Clicking noise from the dash or BCM area when trying to start.

Most Likely Causes

1. Body Control Module (BCM) Software Corruption 🔴 High Probability → Shop Body Control Module This issue is a known problem for vehicles with a 'GEN3R' BCM. A low voltage event (weak battery, jump-start, battery replacement) can corrupt the BCM's memory, causing it to lose communication with other modules. TSB 23-NA-163 was created specifically to address this widespread software problem.
   How to confirm: A professional scan tool will show B3927 along with three or more other 'Incorrect Environmental Identifier' codes (like B3924, B3925, B3926) and often B389A. The presence of this cluster of codes after a low-voltage event is the primary confirmation.
   Typical fix: A special BCM reprogramming procedure must be performed by a GM dealer or qualified shop using GDS2/SPS software, as detailed in TSB 23-NA-163. The BCM itself is not replaced. The procedure involves a specific function named "Programming A Per Bulletin 23-NA-163 and 23-NA-165 Only" followed by an immobilizer learn.
   Est. part cost: $0
2. Weak or Failing 12V Battery 🟡 Medium Probability → Shop Vehicle Battery The battery is not the direct cause of the code, but it is the most common trigger for the BCM software corruption that sets the code. Modern Enclaves with start-stop technology and numerous electronics place a high demand on the battery, making them sensitive to voltage drops.
   How to confirm: Test the battery's voltage and load capacity. A resting voltage below 12.4V or a failed load test indicates a weak battery that needs replacement before the BCM can be reprogrammed.
   Typical fix: Replace the 12V AGM battery. This is a necessary first step before addressing the BCM software, as a new battery is required to prevent the issue from immediately recurring.
   Est. part cost: $200-$400

Diagnosis Steps

1. Confirm the symptoms: No crank/no start and 'Key FOB Not Detected' message.
2. Check the 12V battery. Test its state of charge and health. A weak battery is the primary trigger and must be replaced before proceeding to prevent immediate recurrence.
3. As a temporary measure, try placing the key fob in the vehicle's transmitter pocket to see if the vehicle will start. For the 2018-2024 Enclave, this is located at the bottom of the center console storage area, under any trays or liners. This may bypass the remote antennas and allow the car to start, but it does not fix the root cause.
4. Connect a professional scan tool capable of reading BCM codes (like GM GDS2).
5. Verify that B3927 is present along with at least two other codes from the B3924-B3928 range, and likely B389A.
6. If the code cluster is present, do not replace any parts. The vehicle must be taken to a GM dealer or qualified repair shop.
7. Inform the service provider of TSB 23-NA-163. The technician will need to follow the specific BCM reprogramming procedure outlined in the bulletin, which starts with selecting "Programming A Per Bulletin 23-NA-163" in the Service Programming System (SPS).

Parts You'll Likely Need

• 12V AGM Battery (OEM #ACDelco Gold 94RAGM (GM #88864542)) — A weak battery is the most common trigger for the BCM software fault. It must be in good health before a software fix is attempted to prevent recurrence. The vehicle requires a Group Size H7/94R AGM battery.
  Trusted brands: ACDelco, DieHard, Duralast
  OEM price range: $250-$400
  Aftermarket price range: $200-$350

Related Codes That Often Appear With This One

• B3924 — Part of the same family of 'Incorrect Environmental Identifier' codes that set together during BCM memory corruption.
• B3925 — Part of the same family of 'Incorrect Environmental Identifier' codes that set together during BCM memory corruption.
• B3926 — Part of the same family of 'Incorrect Environmental Identifier' codes that set together during BCM memory corruption.
• P0513 — This 'Incorrect Immobilizer Key' code is set by the Engine Control Module (ECM) because the corrupted BCM cannot send a valid security signal to authorize the engine start.
• B389A — This 'Environment Identification' code is often set in the BCM alongside the other codes and is a key indicator of this specific fault condition per TSB 23-NA-163.

Technical Service Bulletins (TSBs) & Recalls

• 23-NA-163: Provides the definitive diagnostic criteria (cluster of B392x codes) and the specific BCM reprogramming procedure to correct the no-start condition caused by BCM memory corruption. It explicitly warns against replacing modules for this issue.
• 21-NA-277: An earlier version of the bulletin that documents the same 'Incorrect Environmental Identifier' issue, showing this has been a known problem for GM.

Platform-Specific Known Issues

• A known issue documented in GM TSB #23-NA-163 describes how a low voltage event can cause memory corruption in the 'GEN3R' Body Control Module, leading to a no-start condition and setting code B3927 along with others.
• Owner forums for the Enclave and its platform mates are filled with reports of this exact failure after a battery replacement or jump-start, with dealers initially misdiagnosing it as a failed BCM before finding the TSB.

Hidden / Shadow Codes Worth Checking

• B389A 00: Environment Identification. TSB 23-NA-163 identifies this code as a primary indicator that the BCM memory is corrupted. Its presence, along with the cluster of B392x codes, confirms the software issue. (see via A professional scan tool like the GM GDS2 is required. The TSB notes that if B389A is not initially present, disconnecting and reconnecting the battery for 30 seconds may cause it to set.)

Scan Tool Commands That Help

• GM SPS (Service Programming System): Programming A Per Bulletin 23-NA-163 and 23-NA-165 Only — This is the primary software routine to reset the corrupted BCM memory as the first step of the repair.
• GM SPS (Service Programming System): Body Control Module IMMO Learn with Existing Transponder or Remote Key — This immobilizer relearn procedure must be performed immediately after running 'Programming A' to re-sync the existing keys to the newly reset BCM.
• GM SPS (Service Programming System): Programming B Per Bulletin 23-NA-163 Only — This is a secondary, more intensive reset routine to be used ONLY if 'Programming A' and the subsequent IMMO learn fail to resolve the no-start condition, particularly if an immobilizer learn was attempted before the TSB procedure.
• GM SPS (Service Programming System): Engine Control Module and Body Control Module IMMO Learn — This is the immobilizer learn procedure required after running 'Programming B'.
• GM GDS2: Module Diagnostics > [K9] Body Control Module > Identification Information — This function is used to view the BCM's Base Model Part Number (BMPN) to confirm it is a 'GEN3R' module and eligible for the TSB 23-NA-163 procedure.

Wiring & Ground Locations

• G303 — Near the base of the left (driver's side) 'B' pillar.. While the primary cause is a software glitch triggered by system-wide low voltage, a poor or corroded BCM ground could theoretically cause a localized voltage drop at the module itself, mimicking a weak battery and potentially triggering the memory corruption. Checking the integrity of this ground is a valid diagnostic step if the TSB reprogramming procedure fails to resolve the issue.
• BCM Connectors — The BCM is located under the driver's side of the dashboard. It has multiple large multi-pin connectors.. In rare cases where reprogramming fails, a technician may need to test for power and ground directly at the BCM connector pins or check for communication line integrity. Ensuring all connectors are fully seated is a basic but crucial step.

OEM Part Supersession History

• 13594646 → 13534188 — Part has been updated by the manufacturer.
  Heads up: Both original and superseded parts are GEN3R BCMs and are susceptible to the software corruption issue. A replacement module, regardless of part number, will require programming via the GM SPS to function.

Model Year Variations Within This Range

• 2018-2024: TSB 23-NA-163 lists a range of 'GEN3R' BCM Base Model Part Numbers (BMPNs) that are affected. While the failure mode is the same, the specific hardware part number in the vehicle may vary by model year and trim. A technician must use GDS2 to verify the vehicle has one of the affected part numbers before proceeding with the TSB. Affected BMPNs include: 13518569, 13519619, 13519648, 13527252, 13529492, 13533809, and others.