B3925 on 2018-2025 Cadillac XT5: 'No FOB Detected' & No-Start Fix

What's Unique About the 2018-2025 Cadillac XT5

The Cadillac XT5 and its GM C1XX platform mates (like the GMC Acadia and Chevy Traverse) use a specific 'GEN3R' Body Control Module (BCM) that is known to be vulnerable to memory corruption from low voltage events. GM has acknowledged this widespread issue with Technical Service Bulletin (TSB) #23-NA-163, which outlines a specific software-based repair. 🎬 Watch: How BCM issues cause Stabilitrak and Brake Assist errors. This makes it crucial for owners to understand that the root cause is typically software, not a failed hardware component, which can save hundreds or thousands of dollars in unnecessary parts replacements.

Diagnostic Flowchart

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

Symptoms You May Notice

• No-crank, no-start condition
• "No FOB Detected" or "No Remote Key Was Detected" message on the driver information center
• Key fobs are completely inoperative (lock/unlock buttons don't work)
• Engine may start and then immediately stall
• Vehicle alarm may sound when opening the door with the manual key.
• Red security indicator light may be flashing on the dashboard

Most Likely Causes

1. Body Control Module (BCM) Memory Corruption 🔴 High Probability → Shop Body Control Module This generation of GM vehicles uses a 'GEN3R' BCM that is highly sensitive to voltage fluctuations, which can corrupt its memory and security configuration. This is a well-documented issue in TSB #23-NA-163.
   How to confirm: The presence of code B3925 (often with B3924, B3926, B3927) and crucially, code B389A, following a recent jump-start, battery replacement, or period of having a weak battery is a strong confirmation. A professional scan tool is needed to see these codes.
   Typical fix: The BCM must be reprogrammed by a GM dealer or qualified independent shop using the Service Programming System (SPS) software. The technician must follow the specific two-stage procedure in TSB #23-NA-163, which involves 'Programming A' and, if that fails, 'Programming B'.
   Est. part cost: $0
2. Weak or Failing 12V Battery 🔴 High Probability → Shop Vehicle Battery This is the primary trigger for the BCM memory corruption. Modern vehicles have a significant continuous power draw that can weaken batteries over time, and AGM batteries can fail without much warning.
   How to confirm: Perform a load test on the battery. A resting voltage below 12.4V is a sign of a weak battery that may not be able to support the vehicle's complex electronics during startup.
   Typical fix: Replace the 12V Absorbent Glass Mat (AGM) battery. This must be done before or at the same time as the BCM reprogramming to prevent the issue from recurring.
   Est. part cost: $200-$350

Rare But Worth Checking

• Faulty Body Control Module (BCM): → Shop Body Control Module This should only be considered if the BCM physically fails and does not respond to the reprogramming procedure from TSB #23-NA-163. This is very uncommon.
• Poor BCM Ground Connection: A loose or corroded ground wire for the BCM could create a localized low-voltage condition, triggering the memory corruption even with a healthy battery.

Diagnosis Steps

1. First, check the 12V battery. If it's more than 3-4 years old, have it professionally load-tested. A weak battery is the most common trigger and must be replaced to ensure a lasting repair.
2. If the battery is weak, replace it. If it's healthy, ensure it is fully charged before proceeding.
3. Try the backup starting procedure: place the key fob in the designated transmitter pocket located inside the center console cup holder and try to start the engine. This may allow you to drive the vehicle to a repair shop.
4. Do not replace any parts. The issue is almost certainly software-related.
5. Contact a GM dealership or a qualified independent repair shop that has a subscription to GM's Service Programming System (SPS).
6. Inform the service advisor that you have code B3925 and a no-start condition, and request they perform the BCM reprogramming procedure outlined in Technical Service Bulletin #23-NA-163. Mention that codes B389A and other B392x codes are likely present.
7. The technician must verify the vehicle has a 'GEN3R' BCM to be eligible for the TSB procedure.
8. After the reprogramming, all codes should be cleared and the keyless entry/start functions should be tested with all fobs.
9. Only if the BCM fails to accept the new programming should a replacement BCM be considered as a final step.

Parts You'll Likely Need

• 12V AGM Battery (OEM #88864541) — A weak or failing battery is the most common trigger for the BCM software glitch that causes code B3925. The battery must be healthy before the software fix can be reliably applied.
  Trusted brands: ACDelco
  OEM price range: $250-$350
  Aftermarket price range: $200-$300
• Body Control Module (BCM) (OEM #13514637) — Only needed in the rare case that the BCM is physically damaged and does not respond to the reprogramming procedure. Replacement requires programming to the vehicle's VIN.
  Trusted brands: GM Genuine Parts, ACDelco
  OEM price range: $300-$450
  Aftermarket price range: $150-$300

Related Codes That Often Appear With This One

• B389A — This code for 'Environment Identification' is a key prerequisite for the TSB #23-NA-163 repair. Its presence, along with the other B392x codes, confirms the specific BCM memory corruption has occurred.
• B3924, B3926, B3927 — These are companion codes for 'Incorrect Environmental Identifier' from other modules (like the instrument cluster and brake module), which get set when the BCM loses its configuration. TSB #23-NA-163 states that three or more of these codes will be present.
• B1325 — This code for 'Control Module Power Circuit Low Voltage' often accompanies B3925 as it logs the root trigger—the low voltage event that caused the BCM memory corruption in the first place.
• P0513 — This code for 'Incorrect Immobilizer Key' can be set by the ECM as a direct consequence of the BCM being unable to validate the key fob due to the software glitch.

Technical Service Bulletins (TSBs) & Recalls

• 23-NA-163: Addresses a no-start/no-fob-detected condition by providing a specific BCM reprogramming procedure to correct memory corruption that sets codes B3924, B3925, B3926, B3927, and B3928. It requires DTC B389A to be present and applies only to vehicles with a 'GEN3R' BCM.

Platform-Specific Known Issues

• This platform is subject to TSB #23-NA-163, which documents a known issue of BCM memory corruption after a low-voltage event (e.g., battery replacement, jump-start), causing a no-start condition. The official fix is a software reprogram, not hardware replacement.
• Technicians must verify the BCM is a 'GEN3R' type by checking its Base Model Part Number (BMPN) in the GDS2 scan tool before applying the TSB fix. A list of eligible part numbers is provided in the bulletin.

Hidden / Shadow Codes Worth Checking

• B3925 00: The '00' is a symptom byte that means 'General Electrical Failure' with no additional specific information. Its presence aligns with the known BCM data corruption issue outlined in TSB 23-NA-163. (see via A GM-specific scan tool like the GDS2 (Global Diagnostic System 2) is required to view symptom bytes.)

Scan Tool Commands That Help

• GDS2 (GM Global Diagnostic System 2): Module Diagnostics > [K9] Body Control Module > Identification Information — This is the first step a technician must perform to verify the BCM is a 'GEN3R' type by checking its Base Model Part Number (BMPN). The TSB repair only applies to specific, eligible BCMs.
• SPS (Service Programming System): K9 Body Control Module > “Programming A Per Bulletin 23-NA-163 and 23-NA-165 Only” — This is the primary software repair function. It is the first programming attempt to correct the memory corruption that causes code B3925.
• SPS (Service Programming System): K9 Body Control Module > “Programming B Per Bulletin 23-NA-163 Only” — This is the second-stage repair, only to be used if 'Programming A' and a subsequent immobilizer learn procedure fail to resolve the no-start condition.
• SPS (Service Programming System): Immobilizer procedure > “Body Control Module IMMO Learn with Existing Transponder or Remote Key” — This function must be performed after 'Programming A' to relearn the existing key fobs to the newly reprogrammed BCM.

Wiring & Ground Locations

• K9 Body Control Module (BCM) — Inside the passenger cabin, located behind the lower dashboard panel to the left of the steering column. Access requires removing the lower dash trim panel.. This is the module that suffers memory corruption. A technician needs to access its connectors for inspection or replacement if reprogramming fails. GM warns that the BCM can be damaged if a ground path is removed while the battery is connected.
• G103 (example ground) — On older GM models, a common BCM ground point is located on the cowl in the left rear of the engine compartment, above the brake booster. While the exact XT5 location may vary, checking major cowl and A-pillar grounds is critical.. A loose or corroded main ground for the BCM can cause a localized low-voltage condition, which is the root trigger for the memory corruption that sets B3925, even if the battery itself is healthy.

Real Owner Repair Stories

• Reddit user in r/Cadillac (2018 Cadillac XT5) — Vehicle would not recognize the second key fob. Attempting the owner's manual 30-minute relearn procedure caused the vehicle to fail to recognize ANY key fob, resulting in a no-start condition with the message 'Ready for remote 2' stuck on the dash.
  ❌ Tried (didn't work) Changing the key fob battery., Using a new aftermarket key fob., Repeating the 30-minute key relearn procedure.
  ✅ What actually fixed it The story was ongoing at the time of posting, but the dealership had diagnosed a failed Body Control Module (BCM) that needed replacement. This aligns with a rare but possible outcome where the BCM is physically damaged and cannot be reprogrammed per the TSB.

OEM Part Supersession History

• Multiple (see note) → Multiple (see note) — TSB #23-NA-163 applies only to a specific list of 'GEN3R' BCMs identified by their Base Model Part Number (BMPN). The part number mentioned in the Pass 2 data, 13514637, is not on this list, while another common BCM, 13533817, is.
  Heads up: A technician MUST verify the BMPN using GDS2 before attempting the TSB reprogram. Eligible BMPNs include: 13518569, 13518570, 13518602, 13518603, 13519619, 13519620, 13519648, 13527252, 13527260, 13527261, 13527297, 13527298, 13527827, 13529492, 13529493, 13533809, 13533813, 13533814, 13533817, 13533821. If the BCM is not on this list, the TSB does not apply.

Model Year Variations Within This Range

• 2018-2025: The Cadillac XT5 is listed in TSB #23-NA-163 for model years 2018-2025, indicating the potential for this BCM software issue exists across the entire generation, both pre- and post-facelift.