Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC B1009: BCM Internal Memory Malfunction (Checksum Error): Description
Body Control Module (BCM) calibrations are stored in Electronically Erasable Programmable Read Only Memory (EEPROM). When ignition is first turned to RUN position, BCM performs internal tests on EEPROM and determines integrity of its non-volatile memory. BCM will also compare the present checksum with the checksum previously stored.
DTC B1009 will set when stored checksum does not match calculated checksum, or when an internal memory malfunction (checksum error) is detected by BCM when ignition switch if first turned to RUN position. No driver warning message will be displayed.
If conditions for malfunction no longer exist, history DTC will clear after 100 consecutive ignition cycles. DTC B1009 will also clear when conditions no longer exist or when scan tool is used to clear codes.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.