B2920

Code

Generic B — Body

Body Control Module Internal Memory Fault

Brand: Generic

Type: B — Body

Views: UK: 15 EN: 21 RU: 22

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Page language: EN

Causes

Corrupted internal EEPROM/FLASH or bad memory cells
Interruption of power during a write (low battery, sudden power loss)
Poor battery condition or charging system faults (low voltage or spikes)
Faulty BCM hardware (internal component failure)
Software/firmware bug or failed update/reflash
Water intrusion, corrosion or physical damage to BCM or connectors

Symptoms

Illumination of dash warning lights related to body electronics
Intermittent or permanent loss of body functions (locks, windows, interior lights, wipers)
Stored and recurring B2920 or related BCM codes
Modules on the network not responding or intermittent communication errors
Vehicle configuration or personalization settings lost or reset
Possible no-start or immobilizer/key recognition faults on some vehicles

What to check

Read all DTCs and freeze frame data with a capable scan tool; record related U and B codes
Check and record battery voltage (key off and while cranking) and charging system voltage
Inspect BCM connector(s) for corrosion, bent pins, water ingress, or damage
Verify fuses and power/ground circuits to the BCM for continuity and proper voltage
Look for signs of recent software updates or aftermarket installations that may affect the BCM
Attempt to replicate the fault after a known-good battery/voltage condition

Signal parameters

Battery/rest voltage: ~12.4–12.8 V (key off); should not be below ~12.0 V during sleep events
Cranking voltage: typically >9.5 V under cranking load (verify stable supply)
Ignition-switched 12 V supply present when required
Ground resistance: low-ohm connection to vehicle ground (near 0 Ω to chassis)
CAN bus idle recessive voltage: ~2.5 V (differential signals present and healthy)
No excessive transients or voltage spikes on power supply lines

Diagnostic algorithm

Retrieve all related DTCs and freeze frame data; save for reference.
Verify battery condition and charging system; charge or replace weak battery before further testing.
Visually inspect BCM and connector for moisture, corrosion, or physical damage.
Verify power and ground circuits at the BCM: check fuses, supply voltage, and ground continuity.
Check network communication (CAN/LIN) and note any lost-communication codes (U-codes).
If power/ground and communication are good, attempt to clear the code and re-run the system to see if the fault returns.
If code returns, check for recent or incomplete software updates; consult technical service bulletins for reflash procedures.
Use OEM scan tool to attempt a controlled reflash/reprogram of the BCM software if available and recommended.
If reflashing fails or the module still reports memory errors, consider replacement of the BCM following OEM replacement and programming procedures.
After repair or reflash, recheck all related systems, clear codes, and perform function tests to confirm the issue is resolved.

Likely causes

Battery voltage below acceptable threshold during key-off or reflash
Loose/poor ground, power feed or fuse supplying the BCM
Failed or intermittent connectors at the BCM
Previous failed software update or incomplete reprogramming
Internal BCM component failure (EEPROM/FLASH controller)

Fault status

⚠️ Status

BCM detected an internal memory error (corruption, checksum/CRC failure or inaccessible memory). Module may not be able to reliably store or retrieve configuration or runtime data.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0-4.0 hours